'21 View - Truma AquaGo water hammer

Ontario Don · 05-30-2021, 06:56 PM

Hi - Hope everyone is well out there.

Recently the Truma on our '21 View has been hammering when using the water pump.

If I isolate the Truma using shutoff valves, and remove it from the system, all is well. On city water with good pressure, all is well too. Only while on the pump, and now only intermittently, do I get the hammer. It sounds like a check valve slamming when the pump is feeding the heater.

I attempted to increase the shutoff pressure of the pump to see if I could increase delivery pressure to the Truma - and that was partially successful - that is what made the hammer now intermittent.

Thinking it might be a bad pump with inconsistent pressure, I swapped out the factory pump with a spare I have - but that only made things worse. I attempted to adjust the shutoff pressure on the replacement pump, but was not successful in eliminating the racket at all.

Has anyone seen this before?

Many thanks,

Cheers,

sunset · 06-08-2021, 03:03 PM

Same problem with 4-month old View. It started on last trip, primarily in the faucet for the bathroom sink. Initial use of city water caused an overflow in the water heater because of extremely high pressure so I switched to just using the onboard tank. Do not think that I damaged the pump because it was not on.

Ontario Don · 06-08-2021, 03:32 PM

Hi - So, you too are getting a water hammer in the Truma?

I talked with Truma about this last week, and they suspected the delivery pressure to the Truma was too high - as they are aware of the heater getting hammered if under those conditions. Not quite sure what to think, as I experimented with the pump shutoff pressure quite a bit but could not reduce the water pressure significantly, just the duty cycle.

But - Truma recommended I install a pressure regulator in the feed to the pump, which they sell. I ordered one from them, it came the next day (!), I installed it, and I have not had the problem since. You can't find the part in their store, you have to give them a call and order it directly from them. It is 40.00 and installs with standard PEX fittings. Let me know if you are going to do this, and I'll pass on some tips I came up with.

An overflow in the water heater under city pressure? What were the symptoms of that? As for your hammer, your experience is the exact opposite of my scenario - city water for me was Ok; the pump caused my problems. Now, I have an RV pressure regulator installed at the city water inlet... maybe that is the difference. Do you have one of those? This could be a simple 10.00 fix to try first?

Truma indicated that all the racket in the heater was not caused by a valve hammering, just piping under load. I'm glad to see the problem go away, as that was quite a bit of energy hammering in there. Damage to your pump because of the high pressure city water? My opinion would be no, I think it would be very unlikely that the plumbing allowed pressurized water to make it backwards to the pump. Thinking about it some more, if I accidentally leave the pump on when I use city water to the fill the freshwater tank, the pump runs as it sees a drop in pressure and tries to pressurize its feed line. I think you're fine.

Let us know how it goes, best of luck.

Cheers,

sunset · 06-08-2021, 04:18 PM

Too much water pressure from city water hookup? The symptom was that water was gushing out of the overflow valve on the water heater until I turned off the city water. I have a water pressure gauge and control but have not yet used it. I did not figure that it would be a problem at a state park but it obviously was. Rather than mess with it for a 3-night stay, I just used the tank and water pump.

The issue with the water pump was an uneven flow, sort of a sputtering probably more than what I would call hammering (which I associate with a vibration noise). I'll see what happens on the next outing.

crah · 06-22-2021, 04:07 PM

To the Original Poster, thank you for posting the information and the fix you did. I contacted Truma and ordered the pressure regulator that installs by the water heater inlet. That fixed my problem. For anyone else that has a water hammer sound when the pump cycles, but the sound is coming from under the fridge area (24D floor plan), that is the Truma making the sound and not the water pump. I installed the regulator and problem solved. (And this has nothing to do with the pressure regulator at the city water connection). The water hammer sound happens with the water pump. See pictures of the large white pressure regulator installed. I had to cut and modify some of the pex lines, so it wasn't a simple plug and play.

The water pump itself is very quiet and you can barely hear it. Any thunking type of sound is the water hammering into the Truma water heater and can be fixed.

Ontario Don · 06-23-2021, 10:09 AM

Hi - Interesting to know that someone else has also had the water hammer problem with the water heater. Nice installation, thanks for the photo - I had some geometry issues with the location of the Truma in our J model, so had to install the regulator using some flexible braided nylon tubing to give myself some more room.

Glad to hear it solved your problems as well.

Cheers,

crah · 06-23-2021, 06:02 PM

Quote:

Originally Posted by Ontario Don

Hi - Interesting to know that someone else has also had the water hammer problem with the water heater. Nice installation, thanks for the photo - I had some geometry issues with the location of the Truma in our J model, so had to install the regulator using some flexible braided nylon tubing to give myself some more room.

Glad to hear it solved your problems as well.

Cheers,

I'm sure there are many people with the same problem. They just don't know it. I lived with it for 1.5 years but always knew in the back of my mind it didn't sound right. I've never had that issue on previous RV's but they didn't have the Truma. At least the water pump on the View is quiet. The water pump itself is much quieter than my previous RV's. But the water hammering is over the top.