Truma Combi WH winterize

[Granny K]

For those who have the combination furnace/water heater made by Truma:
The video

https://www.youtube.com/watch?v=esq2q3t-4r0

specifies that a bypass kit MUST BE installed if the unit will be winterized with RV antifreeze. My motorhome does not have a bypass kit. I asked FR about this and their response was:

Per Truma who inspects and approves our install it is perfectly fine to run RV antifreeze through the water heater. We do not install a bypass on any unit we install that water heater on. If you have any questions please feel free to contact my office.

Thank you

Dan Dobecki
Class C Warranty Manager
Forester, Sunseeker, Lexington, Solera

So, they disagree! I called Truma's 800 number and they said:

Yes, a bypass is HIGHLY RECOMMENDED! The reason:
Corrosion of moving parts. There is a turbine in the water system to measure water flow, and if it doesn't turn freely the unit will malfunction. She specifically included propylene glycol type antifreeze (corrosion is worse with the ethanol type).

I inquired whether the recommendation had anything to do with a potential fire hazard and she said no, corrosion is the issue.

I believe Truma more than I believe believe Forest River. In fact, if you look on YouTube at other videos (eg.

https://www.youtube.com/watch?v=IcY84lMGpfE

) you will find that a bypass kit is expected.

So I had a three valve bypass kit installed. Pictures show the valve on the cold water line and the valve in the bypass.

[geneowens1]

Hello,
I have the 2371 TS, also a 2017. It seems to have the by pass kit. I was also told by Travis that I could just run antifreeze through the combi but as you say most you tube video's seem to discourage it.
My problem is that the cold water bypass valve is so tight on the floor that I was unable today to move it to bypass. I plan to work some more tomorrow. I did drain the combi tank and got a large amount of water - very likely the 2.6 gallons predicted but I didn't measure. The unit was level when I drained.
Please provide any advice you may have since you've done this already. I had been running heat in my unit but the temps we are getting now make that an issue keeping the unit warm enough.
Thanks,

[Granny K]

Hi Gene! You are the first to post a comment on my thread!

First, glad to hear that you have a bypass kit on your 2371 TS! I guess FR changed their minds about adding one. As you have found, the Truma is located in the void under the sink and is accessible by removing the access panel below the sink. Besides the yellow drain valve for the combi, you should be able to locate a pressure relief valve and a water pipe running between the hot and cold water lines from the water heater, equipped with valves. This is your bypass. Could you post a picture of it?

When I opened the yellow drain valve, a lot of water came out underneath the motorhome but where the outlet is, above the frame of the truck, it dripped everywhere and I couldn't estimate the amount. I applied air pressure and got no further water so I assumed it was empty.

The cold water bypass valve (to admit antifreeze into the cold water lines) was stiff to operate for me but not so tight that I couldn't move it. Is it frozen? Let me know if you're still unable to budge it today.

BTW, our unit has been in storage since October. Temps here have been below -15F.

[geneowens1]

Hello again,
I was able to turn the other valve which was tight on the floor - I had just gotten home the other day from Florida and was just tired. As I said I drained the combi and opened the pressure relief valve. With the by-pass engaged, I tried running RV antifreeze through the hot water side but it still ran out underneath the unit - I closed the combi drain which is outside the by-pass and closed the pressure relief valve - with this done the pump sent antifreeze through the hot side to the kitchen sink [ the farthest faucet from the combi - my combi is under the passenger side twin bed]. Then I ran full antifreeze to the bathroom sink and the shower - I had done the cold water side the other day but not the hot.
I'll take a pic of the by-pass set-up tomorrow and post it.
We have had temps near 10 degrees a couple of times and again tonight. I think I can leave the electric heater off tonight??

[Granny K]

Originally Posted by geneowens1

Hello again,
With the by-pass engaged, I tried running RV antifreeze through the hot water side but it still ran out underneath the unit - I closed the combi drain which is outside the by-pass and closed the pressure relief valve - with this done the pump sent antifreeze through the hot side to the kitchen sink [ the farthest faucet from the combi - my combi is under the passenger side twin bed]. Then I ran full antifreeze to the bathroom sink and the shower - I had done the cold water side the other day but not the hot.
I'll take a pic of the by-pass set-up tomorrow and post it.
We have had temps near 10 degrees a couple of times and again tonight. I think I can leave the electric heater off tonight??

Hi Gene,
Same thing happened to me -- first time I tried running antifreeze into the hot water lines it ran out through the Truma drain valve instead.
You have the other floor plan. I like it a bunch!
Glad to hear you were able to complete your winterization. (Don't forget the outside shower.)
It will be interesting to see the picture of your bypass set-up. The Truma in the 2391 model is under the kitchen sink and VERY difficult to work on. Sounds like you have a much more accessible set-up.
BTW, we are getting brushed by the storm that hit the Canadian maritimes. Temp here has been minus 10 Fahrenheit all day with high winds.