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rapscallion
RO# 31236
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 Posted - Jul 14 2012 : 15:41:41
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The domestic water heater on my boat is discharging warm water into the bilge about 15 minutes after the heater is turned on. The system stays pressurized with no leaks when the heater is off, but as soon as it starts heating the water discharges through the pressure relief valve into the bilge. I checked the temperature of the discharge water and it's barely luke warm, so it can't be a thermostat problem where the water temperature inside the tank gets too high. I'm thinking it must be a faulty pressure relief valve, even though I replaced that component two years ago. Is there some other condition that would cause tepid water to discharge through the pressure relief valve as soon as the unit is turned on?
Thoughts? Vic?
- Raritan 12 gal
- electric
- no heat exchanger from engines
- replaced heating element 3 years ago
- replaced pressure relief valve 2 years ago
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Homeport: Ladner, British Columbia
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Billylll
RO# 24494
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Posted - Jul 14 2012 : 16:12:46
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First how old is the Raritan heater? It sounds like you may have internal corrosion issue that gets into the pressure relief valve and causes intermitent operation and the resulting discharge. Are you sure the HW heater isn't air bound? This could cause faulty operation of the Tstat and the discharge pressure relief valve. What does the Zinc look like, I am assuming the unit has a sacraficial Zinc.
What does the discharge water look like? Have you tried getting your fingers wet and rubbing them together with the discharge water does it feel gritty?
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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rapscallion
RO# 31236
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Posted - Jul 14 2012 : 16:32:21
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I get good flow, no air, with good pressure from the hot side on all faucets with the heater off. The discharge water is clear, but I haven't tested it for grit. Haven't checked the anode. When I replaced the pressure relief valve I didn't see any indication of a corrosion problem. I don't have any record of the heater's age; it was in the boat when I bought it three years ago. I just checked Raritan's site, and they say it could in fact be a faulty thermostat. I learned from Vic at Raritan that the t-stat sits on the outside of the tank and is activated by the tank expanding as the water heats up. It could be that the t-stat isn't working, but that still doesn't really explain why luke warm water is discharging. I would think a faulty t-stat would result in the water overheating and discharging *hot*. But maybe that happened in the past and now the pressure relief valve is no good and is discharging water as soon as any level of pressure builds up. Sounds like I need a new t-stat AND a new pressure relief valve. Or a new water heater.
*Sigh* Big trip with guests coming up in two weeks.
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Homeport: Ladner, British Columbia
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Billylll
RO# 24494
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Posted - Jul 14 2012 : 18:21:32
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Does the hotwater heater still work? Is your only problem a small amount of like warm discharge into the bilge? If so you can probably get by on your 2 week trip. I'm just concerned that if you don't know the age of the heater that it might be time to replace it. I like the larger heaters to me a 6 gallon doesn't give enough time for a muscle relaxing shower. I know my 11 gallon Atwood is just enough for my wife's showering habits. It is more then enough for me. We upgraded when I did the repower 4-5 years ago from a 6 gallon Raritan to a 11 gallon Aluminum cube Atwood heater. I have been very happy with it. The heat exchanger engine option is great as well.
I had to replace mine because it was leaking internally and not through the high pressure relief valve. I wanted the easy to clean rectangular hotwater heater because it fit perfectly and had good reviews.
Here are some pointers that might apply to you hotwater heater from my Atwood .PDF manual.
• Do not place a valve, plug or reducing coupling on outlet part of
pressure-temperature relief valve.
A Pressure Temperature Relief Valve, dripping while the water heater is
running, DOES NOT mean it is defective. During normal expansion of
water, as it is heated in the closed water system of a recreation
vehicle, the Pressure Temperature Relief Valve will sometimes drip. The
Atwood water heater tank is designed with an internal air gap at the
top of the tank to reduce the possibility of dripping. In time, the
expanding water will absorb this air and it must be restored.
WARNING
SCALDING INJURY
• Turn off water heater before opening pressure-temperature relief
valve to establish air space. Storage water must be cool.
TO REPLACE THE AIR GAP FOLLOW THESE STEPS:
1. Turn off main water supply (the pump or water hook up source).
2. Let water cool or let run until cool.
3. Open the hot water faucet closest to the water heater.
4. Pull handle of pressure temperature relief valve straight out and
allow water to flow until it stops.
5. Allow pressure temperature relief valve to snap shut; close faucet;
turn on water supply.
6. Turn on water heater and test.
• At least once a year manually operate pressure-temperature relief
valve (FIG 10).
When pressure-temperature relief valve discharges again, repeat above
procedure. For a permanent solution, we recommend one of the following:
• Install a pressure relief valve in cold water inlet line to water heater
and attach a drain line from valve to outside of coach. Set to relieve
at 100-125 PSI.
• Install a diaphragm-type expansion tank in cold water inlet line.
Tank should be sized to allow for expansion of approximately 15 oz.
of water and pre-charged to a pressure equal to water supply
pressure. These devices can be obtained from a plumbing contractor
or service center.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 14 2012 23:50:22 |
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Homeport: Tuckerton, N.J.
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rapscallion
RO# 31236
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Posted - Jul 14 2012 : 19:16:12
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Billy, my water heater is a 12 gal model. Yup, enough for a decent shower. It's possible the heater is past its useful life, but what's the test for internal leakage? Maybe it is okay and I just need to purge the air gap. I never had this issue in past years though. I'll give it try. Thanks!
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Homeport: Ladner, British Columbia
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boatcomfort
RO# 32076
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Posted - Jul 14 2012 : 19:21:10
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Replace relief valve. They should be tested every year and replaced every 5 years same in your house.
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Homeport: New york
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Audrey II
RO# 30499
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Posted - Jul 14 2012 : 19:29:51
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I have a similar problem mine only leaks while under way. The heat exchangers must get a little hotter then the heating element so on a few hour trip I could dump most on my tank. I need to change the valve but I keep forgetting to pick one up.
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Dave
I just wish common sense was a little more common.
-----------------------------------------------------------
1996 440 Trojan Express
2008 Sea-Doo GTX Jet Ski sold |
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Homeport: Haverstraw, NY
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Billylll
RO# 24494
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Posted - Jul 14 2012 : 19:47:01
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Dave why don't you just turn off your freshwater tanks pump when cruising? You could turn the pump on as needed.
I have a hard time believing you could lose an entire freshwater tank from a "dripping" high pressure relief waterheater valve?
It sounds like yours is busted wide open Dave? I noticed my heat exchanger produced hotwater is a bit warmer then when I am plugged into a 110VAC shore source or the generator is powering the heating element in the Atwood 11 gallon HW heater.
As far as a test to see if the internals are leaking on the Raritan perhaps you should call the factory. Mine was obvious it was leaking all over the place when I had pressurized water to the boat and there was rust all around the old HW heater.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 14 2012 19:53:18 |
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Homeport: Tuckerton, N.J.
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rapscallion
RO# 31236
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Posted - Jul 14 2012 : 20:05:38
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I think he meant he could lose a heater tank of water on a trip, like 6 or 12 gallons, not the entire fresh water tank.
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Homeport: Ladner, British Columbia
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Audrey II
RO# 30499
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Posted - Jul 14 2012 : 20:38:25
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No I lost about 70 gallons on my last trip of about 3.5 hours on the return trip I turned off the fresh water pump but then I can't flush a toilet or wash dishes after lunch. I kept seeing my bilge light coming on I kept thinking the worst until Audrey notice my tank was near empty I felt a lot better it was a big relieve. It's a easy fix I just have to remember to pick out the part it's not like it costs a lot of money!
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Dave
I just wish common sense was a little more common.
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1996 440 Trojan Express
2008 Sea-Doo GTX Jet Ski sold |
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Homeport: Haverstraw, NY
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Billylll
RO# 24494
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Posted - Jul 14 2012 : 21:15:30
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Hum Dave if it's that bad you also have a chance of destroying the hotwater heater if you run out of tank water while the HW heater has AC power on. You could still flush etc just turn the pump on and off before and after each need for pressurized tank water. Come on Dave fix that valve before a fairly inexpensive part costs you a heating element.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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Sandy
RO# 1159
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Posted - Jul 14 2012 : 23:44:07
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rapscallion - It's probably just semantics, but I noticed Bill's detailed post above explains how to add the air gap back in to act as accumulator/pressure tank effect, able to lessen the impact of expanding heated water. But you mentioned you were thinking of purging the air gap ....which sounds like the opposite of what is needed, at least for Bill's heater. Just didn't sound quite right.
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| Sandy |
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Homeport: The Vineyard
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rapscallion
RO# 31236
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Posted - Jul 15 2012 : 18:24:50
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Right: restore the air gap, not purge it. Thanks Sandy. My boat has an accumulator tank so I'm not sure if the procedure applies to my situation, but I can't see it hurting to try.
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Homeport: Ladner, British Columbia
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Billylll
RO# 24494
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Posted - Jul 15 2012 : 18:45:09
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I think the concept would work with most hotwater heaters. Too bad Vic isn't around much anymore since he retired from Raritan. I don't think it will hurt trying. If it doesn't work I would replace the valve.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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JimPend
RO# 5022
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Posted - Jul 15 2012 : 19:12:10
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Air gap or no air gap the pressure is still the same. I think you need to replace the relief valve.
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| Jim P. |
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Homeport: Port Clinton, OH
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cmariner32
RO# 7269
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Posted - Jul 15 2012 : 21:38:16
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Vic is no longer with Raritan? I wondered why he didn't respond to my post in the plumbing forum. Is anyone gonna take his place>
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| The only thing that works on an old boat.....is the Owner. |
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Homeport: Clearwater/St. Pete Florida
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Veg
RO# 20854
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Posted - Jul 15 2012 : 22:58:46
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I had that issue last year, I replaced the relief valve and all is good now.
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| 2001 Tiara 2900 Open - "O Sole Mio" - Stillwater, MN |
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Homeport: Stillwater, MN
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meide
RO# 13472
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Posted - Jul 16 2012 : 00:21:17
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Jim.
Actually a small air gap will make a large difference in the tank pressure as the water heats up. With no air gap the incompressible water will create very large pressures when it expands due to the increased temperature. The water does not need to expand very much to cause a huge pressure change if there is no air gap.
With an air gap the water can expand and compress the air. But since the water expands very slightly there will only be a small pressure rise.
Mike
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Homeport: Pasadena MD
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Billylll
RO# 24494
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Posted - Jul 16 2012 : 01:29:02
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quote:
Originally posted by cmariner32
Vic is no longer with Raritan? I wondered why he didn't respond to my post in the plumbing forum. Is anyone gonna take his place>
Yes Vic has been gone from Raritan about 6 months now, Last time I saw Vic he stopped by the house to talk.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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Billylll
RO# 24494
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Posted - Jul 16 2012 : 01:33:15
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quote:
Originally posted by meide
Jim.
Actually a small air gap will make a large difference in the tank pressure as the water heats up. With no air gap the incompressible water will create very large pressures when it expands due to the increased temperature. The water does not need to expand very much to cause a huge pressure change if there is no air gap.
With an air gap the water can expand and compress the air. But since the water expands very slightly there will only be a small pressure rise.
Mike
+1 the lack of the air gap or expansion room can lead to premature failure of the pressure relief valve.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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Billylll
RO# 24494
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Posted - Jul 16 2012 : 01:37:11
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quote:
Originally posted by rapscallion
Right: restore the air gap, not purge it. Thanks Sandy. My boat has an accumulator tank so I'm not sure if the procedure applies to my situation, but I can't see it hurting to try.
The accumulator tank is on the feed after the pump that feeds the entire cold and hotwater systems (to the HW heater) it's in the wrong place for this issue if that's your problem.
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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OLD HOUSEBOATER
RO# 9099
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Posted - Jul 16 2012 : 08:49:57
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Once the relief valve goes off the first time it won't seal as good as it should and be replaced.
Water expands as it is heated. If you have no air cushion it has no place to go except the relief valve. If you have engine heat exchanger assist, the temperature is much greater when running. This sometimes sets off the temperature feature of the valve.
NOTE: THIS HIGHER TEMPERATURE CAN CAUSE SCALDING DANGER. Heater setting is around 125 to 135 degrees. Engine assist can exceed 170 degrees. This option has fallen out of favor in recent years due to this possibility.
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OLD HOUSEBOATER
The French fries are cold so we gave you extra. |
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Homeport: GULF SHORES AL.
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rawidman
RO# 25110
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Posted - Jul 17 2012 : 09:04:08
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1) Replacing the TP valve if it is leaking is the first step. Even if it was replaced a few years ago.
2) If the heater is plumbed to the engine's cooling system for water heating while underway and if the engine is fresh water cooled, the temperature can reach 180 degrees or even more. Turning the water pump (on the potable water system) "OFF" and opening a hot water faucet (to relieve the pressure) while underway is a good idea.
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Ron
2000 Camano Troll |
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Homeport: Charleston, SC
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Billylll
RO# 24494
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Posted - Jul 17 2012 : 09:21:10
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quote:
Originally posted by rawidman
1) Replacing the TP valve if it is leaking is the first step. Even if it was replaced a few years ago.
2) If the heater is plumbed to the engine's cooling system for water heating while underway and if the engine is fresh water cooled, the temperature can reach 180 degrees or even more. Turning the water pump (on the potable water system) "OFF" and opening a hot water faucet (to relieve the pressure) while underway is a good idea.
There you go again Ron coming up with a practical solution! Good idea.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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Reel Antsy
RO# 9587
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Posted - Jul 17 2012 : 09:25:20
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quote:
Originally posted by Veg
I had that issue last year, I replaced the relief valve and all is good now.
Plus one, same exact issue. Replace relief valve, all is well.
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Jamie
1985 Trojan F32
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Homeport: Rockville, MD / Colonial Beach, VA
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KiDa
RO# 16492
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Posted - Jul 17 2012 : 11:33:01
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Agree with replacing the pressure relief valve as well. I believe the pressure reilief valve is a one shot deal. Once they pop, they never work the same again.
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____________
Best Regards,
David
Saint Max
'99 330 Sundancer
==========
Capitalism is to this administration what Judaism was to the Third Reich.
-- Me |
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Homeport: Hopewell, VA
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Billylll
RO# 24494
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Posted - Jul 17 2012 : 15:41:32
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On my Atwood the above proceedure is done every year. So I can say popping the valve has not caused mine to leak. See steps 4 & 5 of the factory proceedure I posted above. I think step 4 keeps crud from getting into the pressure relief valve. I am on my 6th season and so far so good. Now I'm probably tempting fate with the HW heater!
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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JimPend
RO# 5022
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Posted - Jul 17 2012 : 18:07:30
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meide, That is not right presure is presure, water or air, the only difference would be the presure drop with no air gap would be immediate, that's what surge tanks do, even out the pump cycle.
There must be a one way valve on the water heater ( not the hotwater heater, no need to heat hot water) I removed my one way valve and put in 10 feet of extra hose solved the delta presure problem in the boat.
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| Jim P. |
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Homeport: Port Clinton, OH
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meide
RO# 13472
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Posted - Jul 17 2012 : 21:01:27
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Jim,
You are correct until you change the temperature of the water in a closed system. If you raise the temperature of a full container of water the water will expand slightly, but since the water is incompressible it will cause a huge increase in pressure. If the container is very rigid (steel or aluminum) you can create pressures of several thousand PSI and burst the tank.
Do the same thing with a small air gap and the results are vastly different. The water still expands a small amount as the temperature rises. This small expansion compresses the air only a small amount, resulting in a tiny rise in pressure.
This is precisely why you drain water lines and tanks before they freeze. If the water is constrained in a fixed container or pipe the pressure rise is enough to cause structural failure. Leave an air gap and the pressure increase is almost completely eliminated.
Mike
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Homeport: Pasadena MD
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Billylll
RO# 24494
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Posted - Jul 17 2012 : 21:14:36
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quote:
Originally posted by meide
Jim,
You are correct until you change the temperature of the water in a closed system. If you raise the temperature of a full container of water the water will expand slightly, but since the water is incompressible it will cause a huge increase in pressure. If the container is very rigid (steel or aluminum) you can create pressures of several thousand PSI and burst the tank.
Do the same thing with a small air gap and the results are vastly different. The water still expands a small amount as the temperature rises. This small expansion compresses the air only a small amount, resulting in a tiny rise in pressure.
This is precisely why you drain water lines and tanks before they freeze. If the water is constrained in a fixed container or pipe the pressure rise is enough to cause structural failure. Leave an air gap and the pressure increase is almost completely eliminated.
Mike
+1
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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rapscallion
RO# 31236
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Posted - Jul 29 2012 : 23:32:39
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Replaced the pressure-temperature relief valve. Problem solved. Props to Kim at Raritan for talking me out of buying a thermostat and p-t valve from them. She told me to just replace the p-t valve with one I could get at a hardware store. Did that; no more problem. Out on the boat now; water heater's working great. I appreciate that kind of service from a manufacturer.
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Homeport: Ladner, British Columbia
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lobsta1
RO# 1808
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Posted - Jul 30 2012 : 11:02:33
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I believe Vic Willman said using a household PT valve is a bad idea as they are rated for 150 psi. Most boats have plumbing rated at a much lower psi.
Al
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| 1978 Bertram 33 |
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Homeport: Beverly,Ma
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rapscallion
RO# 31236
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Posted - Jul 30 2012 : 11:16:38
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Yes, Kim at Raritan told me it's not recommended but lots of people do it. After this trip I'll replace it with one rated at 75 psi.
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Homeport: Ladner, British Columbia
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Veg
RO# 20854
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Posted - Jul 30 2012 : 11:44:45
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Well, FWIW, my water heater is Atwood, and they use 150 psi. When I changed mine, I communicated with them asking where I could get a 75psi for it, and they told me that they use 150psi and that that's what they recommended I use, and they even gave me the part number. So my original on the boat was 150, and I replaced it last year with 150. Never had a problem with it (other than the mentioned valve replacement last year).
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| 2001 Tiara 2900 Open - "O Sole Mio" - Stillwater, MN |
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Homeport: Stillwater, MN
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Billylll
RO# 24494
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Posted - Jul 30 2012 : 12:20:57
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I also have an Atwood and follow the commisioning proceedure above every year I never leak a drip from the high pressure relief valve.
Bill
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WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Homeport: Tuckerton, N.J.
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pdecat
RO# 842
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Posted - Jul 30 2012 : 12:46:06
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in addition to the pressure issue houshold units dont get as hot as engine heated boat units.
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Bruce
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Homeport: Gulf Coast FL
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Vic Willman
RO# 3655
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Posted - Aug 07 2012 : 21:53:37
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I'm still on the Forum occasionally, just not as often as before. Yes, I'm retired now and doing a fair amount of traveling before I get too old to do it (turned 70 in June).
Give Raritan a call, and see if they still offer a 100 psi replacement pressure relief valve. I don't remember the part number, possibly #WH1G, but not sure any more. Their 75 psi pressure relief valve tends to pop off more than we'd all like. We never recommended stepping up to the 150 psi model used in household water heaters because while the water heater tank can carry the pressure, your connecting lines may not be able to. I'd be especially wary of the gray plastic lines with the push-in fittings. A line blowing out when you aren't onboard can cause REAL PROBLEMS.
Also, for general information purposes, the female thread for the pressure relief valve on ALL Raritan water heaters is a 3/4" pipe thread, NOT a 1/2" pipe thread.
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| -- The Head Master -- |
Edited by - Vic Willman on Aug 07 2012 21:56:52 |
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Homeport: Millville, NJ
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| BoaterEd |
© 2010 BoaterEd, Inc. |
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Water heater discharging into bilge
