Community Forums

jimshawn73 · 10-29-2015, 07:02 PM

Hi Group,
Somewhat new to this group and we are seeking some advise and help with a Atwood Model #GC10A-4E water heater in our 2008 Newmar Grand Star. The water heater lights when we start it, but we do not get really hot water at any of the taps (shower, vanity, kitchen sink) It is warm, but not hot. You can leave it run and it never needs cold water to be bearable. What is the recommended fix for this? Thanks for any help.
Jim & Shawn

ftum · 10-29-2015, 07:17 PM

My Atwood did the same thing I was told to go outside and make sure the "outside shower" valves were completely closed. I did give the valves another turn (even though no water was dripping) and this solved my "lukewarm water" problem .

jimshawn73 · 10-29-2015, 07:27 PM

ftum,
we checked all those and there is nothing to drain off any hot water at all.
not sure if there might be thermostat issues or sediment in the tank or thermostat control problems.
thanks for the reply.

markmiiler · 10-29-2015, 07:30 PM

I had the same problem on maiden voyage with our 08 Damon Tuscany. I have a actwood and the water heater was hot but could not get hot water of it. The problem was the mixing valve on heater. The valve was adding to much cold water to the hot water before dispense coach. I bypassed the valve as a temp fix but it will deplete hot water very quickly

markmiiler · 10-29-2015, 07:33 PM

The pop off valve can be released a little to check water in tank is hot. Be careful as it will be extremely hot water. This will signal mixing alve faulty.

nothermark · 10-29-2015, 07:43 PM

FWIW the issue with the hand shower outside (or any shower) is that if you push the slide valve to shut off the water at the shower head but leave the feed valves open then the cold can mix into the hot side as it feeds another line. That is why it is good practice to leave the slider in the middle so the handle will drip if one is not sure which way is off.

The same thing can happen with the valving for the hot water bypass. If the center valve in a 3 valve system is open blending will occur. Not sure how the single valve with a check valve system works but have heard a failed check valve can cause problems.

ftum · 10-29-2015, 07:52 PM

Quote:

Originally Posted by jimshawn

ftum,
we checked all those and there is nothing to drain off any hot water at all.
not sure if there might be thermostat issues or sediment in the tank or thermostat control problems.
thanks for the reply.

I had called an rv parts store to get a new thermostat. The salesman said if I had "lukewarm"water he could guarantee that it was not the thermostat.. he insisted there would be a hot or cold water valve not completely closed somewhere. Hope you solve this, it was frustrating for me.

jimshawn73 · 10-29-2015, 07:54 PM

mark miiler,
we will have to check out the mixing valve if there is one and where it might be. the PO valve has not gone off, so not sure there either.
nothermark,
the shower we are using inside, does not have a single/mixing valve set up. two knobs and we have tried just hot only with just warm water output.
thank you both.

jimshawn73 · 10-29-2015, 08:01 PM

ftum,
it sure is frustrating for us. water heaters should either put out hot water or not!!
another test for us tomorrow.
thanks....

nothermark · 10-30-2015, 04:59 AM

FWIW I said the inside shower can do the same thing. It will not if you are using it as the slide valve is open so you can get water out. There is no mixing valve as such. What happens is you have a hot and a cold line each connected to the same spot though the valves in the lines. The differential in pressure in each line sets up mixing through the common connection when another valve is opened somewhere else in the system.

markmiiler had a good point. Trip the pop off valve and carefully see how hot the water is coming out.

We recently also had a report that somebody solved a similar problem by replacing the thermostat and/or control board. All can fail in a way that will give you cooler water. Some are just more likely than others.

jimshawn73 · 10-30-2015, 08:36 AM

well group, I think I might have it fixed. this morning, I checked the piping setup at the heater. there is a valve on a bypass between cold in and hot out right at the heater and that valve was open. when I closed the valve, there is plenty of real hot water now coming out of all spots now.
next question would be, why would that valve be there and should it have even been in the open position at all? will it cause other problems if we leave this bypass valve closed at all times?
thanks again for all the feedback.

ftum · 10-30-2015, 02:46 PM

Quote:

Originally Posted by jimshawn

well group, I think I might have it fixed. this morning, I checked the piping setup at the heater. there is a valve on a bypass between cold in and hot out right at the heater and that valve was open. when I closed the valve, there is plenty of real hot water now coming out of all spots now.
next question would be, why would that valve be there and should it have even been in the open position at all? will it cause other problems if we leave this bypass valve closed at all times?
thanks again for all the feedback.

Hope someone will explain what that valve is for. (May have something to do with winterizing) Anyway, glad you have hot water, yeah!!

jimshawn73 · 10-30-2015, 03:24 PM

what we did find out though many google searches is indeed that bypass is for winterizing and flushing the heater. and it also appears that the normal position is closed.
our unit does not appear to have a "mixing valve" or one we could find either. from what we have read, those mixing valves have a factory set temperature that allows cold water to mix with the hot water in order to conserve the limited amount of hot water in the tank. even though it is a 2008 model, that is not new enough or Newmar elected not to install on this Grand Star.
also, after thoughts about who or why this valve was in the open position, we did take the unit right from it's winter storage to be serviced. the service location also did a pressure check of the water system and they might have opened the valve.
so, lessons learned again and hopefully sharing this with the group here, others might save some grief chasing repairs that are as simple as closing a valve!
thank you again to all that have replied and posted.
the wife is REALLY happy now that we have HOT water and lots of it!!

nothermark · 10-31-2015, 05:29 AM

Quote:

Originally Posted by ftum

Hope someone will explain what that valve is for. (May have something to do with winterizing) Anyway, glad you have hot water, yeah!!

What you have is a typical 3 valve setup for making something removable without shutting down the system. I saw them in industry on tanks long before I saw them in a MH. The basic idea is to put a valve into each leg of the tank then put a bypass across the top of the valves with a third valve in the bypass. If one wants to service the tank one opens they bypass and closes the two feed valves effectively removing the tank from the system.

In your motor home you close the two feed valves and open the bypass when winterizing so you can drain the HW tank while keeping the plumbing integrity for putting in antifreeze. As you have noticed that has to be reversed completely when de winterizing.

The other gotcha is that those valves are essentially a ball valve with a cavity in the ball filled with water. When winterizing open each feed valve for a second or two when the system is under pressure with the antifreeze. That pushes the water out of those cavities so the ice does not crack the side of the valve body. ;-)