Pulsing water pump only when using hot water (at altitude)

[txloser]

We’re dry camping currently at 9500’ so I don’t expect peak performance from my water pump or Furion Tankless. However, we’ve been here before and while the max temp of hot water was less, the flow was consistent.

This time, using cold water only, pump runs, and remains running till you cut off the water. Pressure seems normal. Using the hot water(full hot/no mixing) at any fixture, the pump pulses which has the side effect of the Furion temp being erratic and struggling to get warm.

The pump obviously works ok. No leaks as it doesn’t run spontaneously when sitting idle. On city water everything works fine. Or at least it did before we got here.

Suggestions?

 

[txloser]

Ok, so for anyone else in this situation I figured out a work around. Best I can tell, my pump moves with more pressure than the Furion needs with any fixture to full hot, so it build pressure and cuts out. So, instead of 106 degrees on full hot at a fixture, I set 124 and mix. This keeps the pump running gives me up to 115 degrees at this altitude.

 

[Soundsailor]

Thanks for reporting your self-found solution. I've changed the thread title to reflect altitude.

 

[Jomani]

Did you happen to adjust the flow control valve on the water heater to “Min” at some point? While that will help to increase the efficiency of the burner assembly by slowing down the water, it can also cause the water pump pulsing that you are experiencing with hot only.

By design, the tankless water heater does create some resistance to water flow. Although I wouldn’t expect to see it on a 2024 model, scale buildup will further increase that resistance. What you are experiencing may be a sign that it is time to descale the water heater. There is also a check valve on the output (hot water side) of the water heater than can cause this problem.

I am actually impressed that you are getting those kinds of temperatures at that altitude. According to the manual, the water heater was only tested to 4,500 ft. It would be great to hear back if you figure out what changed, but happy to hear that you found a workaround.

 

[huntindog]

Wow, 95% of our camping is over 4500'. with that, and and it not working in cold weather, and no more propane fridges, they are ruining RVing for us. I am going to keep what we have a long time

 

[txloser]

Did you happen to adjust the flow control valve on the water heater to “Min” at some point? While that will help to increase the efficiency of the burner assembly by slowing down the water, it can also cause the water pump pulsing that you are experiencing with hot only.

By design, the tankless water heater does create some resistance to water flow. Although I wouldn’t expect to see it on a 2024 model, scale buildup will further increase that resistance. What you are experiencing may be a sign that it is time to descale the water heater. There is also a check valve on the output (hot water side) of the water heater than can cause this problem.

I am actually impressed that you are getting those kinds of temperatures at that altitude. According to the manual, the water heater was only tested to 4,500 ft. It would be great to hear back if you figure out what changed, but happy to hear that you found a workaround.

We’re at 8500’ feet now and still 115 is best I can get, but since we’re on city water I’m keeping it at 108 and not mixing. Plenty warm and working great on city. My water pump puts out some serious pressure which is nice, but I think the restrictive nature of the Furion was biting me and I’m too lazy to go downstairs and adjust the pressure down.

I tried to adjust the flow control. Visually it’s set to max. But, I can’t get the thing the budge. Maybe it needs the pressure zeroed out to adjust, or something else is going on.

At a little over a year old I should descale. Also, an idiot move on my part, when I bought the trailer I thought the filter sitting in the basement was a spare. I went 8 months with no water filtration. So who knows what’s in the system.