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Old 10-26-2009, 01:35 PM   #1
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Tropical Hot Water Heater By Pass

Have just purchased a 1997 Tropical and I am not familiar with the one valve hot water heater by pass system - I'm getting ready to winterize but before I do I would like to get some info on this by pass system.

Any RV's I've owned either had a 2 or 3 valve system for by passing the HWH.

Can anyone explain how this one valve by pass system works without letting water continue to flow through the HWH?

Any input or help would be greatly appreciated

Thanks all.
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Old 10-26-2009, 03:03 PM   #2
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Sunny
You could have a
Watts 1/2" PM Plumbing Module


Watts user friendly, 1/2" PM Plumbing Module for OEMs, does away with any confusion when operating RV plumbing systems by use of a three position, single handle control. Hose jockeying during the change over from tank filling to city water operation is also eliminated by one hose connection for all uses. Annual draining and winterizing procedures are simplified, be-cause the entire system can be drained or blown out through a single port. The option of taking winterizing fluid from its container by use of the RV system pump frees the end user from the mess and bother of conventional practice. Fi-nally, water heater bypass installation and operation is significantly facilitated with the 1/2" PM.
RV manufacturers will appreciate the dependability, reduction of space and weight, and easy installation this device offers. The patented 1/2" PM is fabricated under ISO 9001 standards, and IAPMO and CSA approvals are pending.

installed on your coach. My 1999 Tradewinds does. This unit does all the work of multiple valves for Hot Water Heater bypass.

I'll include a scanned picture from my owners manual.

Or you could have the plumbing arrangement in the second attachment. This is a three way valve that shuts off the input to the HWH and connects it to the output with a "Check Valve" installed on the output to prevent water from entering the HWH.
Both methods were used by National around the time your coach was made.
Dick
BTW: Nice choice of coach. How long have you had it?
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Old 10-26-2009, 04:23 PM   #3
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Thanks for the reply - my unit's HWH bypass isn't that "exotic" and I know it's not the second one either.
There is simply one valve between the hot and cold water input/output. I think I may have read somewhere that this may be accomplished with check valves but haven't been able to find out for sure if that's in fact what National did.

Yeah - we really like it - bought it about a month ago - it's a 236L widebody (no slides) but tons of interior space with the L shaped living room.
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Old 10-26-2009, 06:03 PM   #4
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Glad you like your rig. The HW Bypass must have a check valve somewhere in the hot water output or it would just fill in the output.

Dick
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Old 10-28-2009, 08:30 PM   #5
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My 1997 Dolphin also has a single value bypass system. I have had the unit for 4 years ... only this year did I have any problem winterizing it. I don't know the procedure I followed the first three years, but this year I drained the water heater first and left the plug often. I was pumping antifreeze and asking DW if she was seeing color ... after a gallon, I realized it was pumping out the water heater. I thought I must have not turn the bypass on. Still pumping antifreeze. Kept changing the position of the value. Anyway, finally put the water heater plug in and pumped antifreeze through the lines. When I drained the water heater, there was air pressure but not a lot of antifreeze.

I will have to check to see if there is a check valve on the heater output side. We did pickup some sand in Florida last winter so it could have screwed up a check valve.
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Old 10-28-2009, 09:48 PM   #6
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That sure is a logical place to start the search. The check valve doesn't have to be right by the water heater, it could be behind the panel your valve is on. Just a choice made by National. Although I like the way mt Tradewinds is built, I don't always understand the choices National made in the design.

Dick
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Old 10-29-2009, 10:44 AM   #7
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Thank you both for your input -
I'm not sure that I'm totally on board with this single valve system and check valves but I guess National had their reasons for doing it this way. Seems to me a 2 or 3 valve HWH by pass would simplify things especially when things go wrong. Check valves in a closed system like an RV IMHO are just asking for problems. They are subjected to water with high mineral content and all sorts of "nasty" things that can render a check valve useless in no time either by sticking it open or worse yet closed.
I think next spring I will be replacing this one valve wonder with a two valve HWH by pass - then I'll know for sure when the bypass is "active" or not.
I hope as Dick suggested, that the check valve(s) aren't behind the panel, but rather are within close proximity to the HWH. The bypass valve is right by the HWH so I'm assuming that any check valves for this bypass system would have to be on the downside of the HWH.
In any case it's a bit confusing and National's Owner's manual really doesn't explain the workings of the HWH bypass in any great detail and their diagram of the water system is not all that great either as it doesn't show the actual connections from the HWH to the rest of the system (it's just in it's own little diagram but doesn't show how it's tied in to the system or water direction). A diagram with red and blue water lines (for hot and cold) would have been great along with arrows for water direction.
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Old 10-29-2009, 11:26 AM   #8
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The one valve is what is called a 3-way valve.. It takes water in via one port and sends it out to either one of the other two ports.. When the port that goes into the water heater is selected that is the "USE" position, the other port goes straight up to the hot water out line where it is connected via a "T" fitting, this is the bypass port.

On the outlet of the heater is a common check valve

In the USE position water flows into the heater, usually near the bottom, then hot water (if it's been heated) flows out via the check valve into the plumbing.

in the bypass position cold water flows around (Past) the heater to the hot water lines and the check valve prevents it from entering via the heater outlet.

2 valve systems replace the check valve with a quarter turn valve

3 valve systems use the quarter turn on the heater outlet
And use a pair of single quarter turn valves to replace the 3-way (This is less expensive and frankly I like it better)

Does this help

Side note: Had a couple of campers mention they had very little hot water flow.. they are full timers and never winterize.. The check valve I mentioned....... All calisified and when they took it apart

Worked fine. They are not putting it back together since they will nto winterize and thus don't need it.
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Old 10-29-2009, 03:36 PM   #9
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To get to the water heat bypass, I have to pull a kitchen drawer out next to the refrig. It sure looks like a check value, a little larger than an adapter. Went to our home improvement store (Menard's) and could not find one the same size. Oh well, no problem until next year
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Old 10-31-2009, 12:59 PM   #10
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Thanks everyone for all the input.
I can see that heavy mineral deposits would have a rather adverse effect on check valves - maybe running some vinegar or CLR through the lines would help get rid of some of the deposits in the check valve, but it would have to be super clean in order to work the way it's supposed to. Any little bits of mineral deposits left are going to keep the check valve from closing properly and allow slow and bothersome leaks past the check valve. This would mean that there would always be the chance of getting anti-freeze in the HWH thus rendering the bypass virtually useless or worse yet - no hot water when needed.
I still think in the spring, I'm going to install a different HWH bypass set up - "simple is better" and I would have to say that in theory this set up was a good one (when it's working properly and new from the factory) but I think National would have been better off to simply install a simple two or three valve HWH bypass without the need of check valves that can become troublesome down the road.
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Old 10-31-2009, 03:03 PM   #11
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Glad you found it. The hardest part is getting to it. But it may be simple to replace it with a valve. One where the check valve is will do the trick. You'll just need to run it out where you can get to it. That would just be flex hose and fittings.

Dick
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Old 11-02-2009, 11:31 AM   #12
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Thanks Dick
Actually on mine the rear of the HWH is real easy to get at - almost under the galley sink. Now just to figure out where the actual check valve is??
Likely will just need a closer look and it should be between the bypass valve and the input side of the HWH.
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Old 11-02-2009, 04:20 PM   #13
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Quote:
Originally Posted by sunnysouth View Post
Thanks Dick
Now just to figure out where the actual check valve is??
I have a 1997 Dolphin 536 ... the only difference is the bed is cross-ways. The check value appears to be on the outlet of the hot water heater. there is a check value and a nipple reducer. Good luck
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Old 11-03-2009, 10:06 AM   #14
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Thanks Never

I guess the important thing is to make sure when I change everything over to a different HWH bypass is to make sure the check valves are removed as they (it) would no longer be needed.
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