[Andy]

Dick, Dont forget the colder the supply water to the water heater the more it will expand when heated to a given temp. If your keeping your water bay at 40 degrees you will be getting much more expansion than in the summer when its 60. If your expansion tank air pressure is a bit off or marginally sized for the system(for example) it may only give you problems when its cold. Im not saying hold out for summer or you dont have an issue. Im just saying if you havent used your coach in this cold of temps the issue may have always been there. Jeff

[Archived]

I have used the coach in temps like this, but maybe not with this water heater.

[Dick]

Dick, Do you know the proper procedure for checking your expansion tank pressure?

[DON]

My Groco pump is 12V and cost over 200.00 per Volt.

[Dick]

Jeff: I don’t think we have an expansion tank. I haven’t been able to find it yet.

[Andy]

Dick, if your bus is like mine, the expansion/accumulator/DIAPHRAGM tank is in the water bay with the pump, HW heater, etc. It’s probably BIG and blue and may say A O Smith on it(see pic). The model of mine is a Hydro-Pro # V15P. See p.2 of the following link

http://www.watertanks.com/content/pdfs/watertankscom-goulds-hydropro.pdf

It has a Schrader valve on it so as to check and fill the air pre-charge. With zero pressure in the water system, precharge should be 18 psi. To set pre-charge, open faucet(s) and let all the pressure out. Then set diaphragm tank pre-charge to 18 psi. Turn on the pressure pump till it shuts off, then re-check the pressure. Mine reads 50 psi.

I hope this helps

[Roscoeapproved]

That’s the kind of thing I’ve been looking for, but haven’t found. I’ll check to see if there are any artifacts left in the coach which might have been used to mount the blue device if a previous owner removed it. Thanks!

---

Jeff and Lindsay

91 Marathon XL

[Andy]

To my knowledge the air should be set to 2psi below the pump cut in pressure set in the manor Don described. If the pump is set to come on at 20psi i would agree with Dons number of 18. Best to check and charge accordingly.

[Archived]

The information about accumulator tank pressure is correct. To set the pressure turn off the pump and open a faucet. When the water stops running you can check and adjust the pressure.

If the water runs for a while with the pump off the chances are the accumulator pressure is pretty close to where it needs to be.

Until this coach my accumulator tanks were as shown in the photo above. I know I have one but I cannot find it, but so far it must be OK because the water runs a long time with the pump off.

I did add a second one dedicated to the Headhunter toilet so with the sytem fully pressurized I could get a complete flush with my small back up water pump.