Atwood Tankless Water Heater - Will Only Ignite When I Turn On the Bathroom Sink

[sonyamontana]

Hello Airstream Officianados - we recently purchased an Atwood Tankless Water Heater (50,000 BTU) and had it professionally installed. Here is the situation - the hot water heater only ignites when we run hot water out of the bathroom sink. I have tried so many configurations and just can't get the unit to ignite when I run the shower or kitchen sink. It tries (I hear clicking) but it doesn't fire up. We have a 26T 1968 Airstream - so the bathroom sink is closest to the hot water heater. I can get hot water to the shower and kitchen sink ONLY IF I run the bathroom sink at the same time. Here are some other specs to consider: we are running off of well water (garden hose connected to the trailer); we have a pressure reducer on that inlet (30-40 psi); the trailer was recently (a couple of owners ago) replumbed with Pex pipe; and I have the Atwood Unit Modulator Valve in Max position. I've checked the propane level - full tank; filled the water tank in the airstream in case that had anything to do with our water pressure moving through the tank; confirmed the water pressure is at least 30 psi from the hose. What am I missing? Any ideas? I'm dying for a hot shower! Thank you all in advance!

[rmkrum]

Lose the pressure reducer if it is one of those cheap fixed ones. I found they don't allow enough flow for my PrecisionTemp heater under most conditions.

I replaced it with a fully adjustable one with a pressure gauge on it.

Also check and clean the strainer/aerator on the faucet. That can cause low flow.


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[ijustlee]

You probably are not getting enough flow through the heater to work the ignition control. A call to Atwood tech support might help. As a professional handyman I'm biased against tankless water heaters in general because a control mechanism has to actuate every time you open a hot water valve. A lot more problems than with the old fashioned tank types.

[rmkrum]

My experience has been stone cold reliability and happy wife, who loves her hot showers. Happy wife is priceless, IMHO.

Have one at home as well.


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[HiJoeSilver]

Use a pitcher and timer to see how much flow you're getting through the kitchen sink, hot only. The tankless wh's need a minimum flow, usually 1-1.5 gpm otherwise they won't light.

This minimum flow is why when anybody asks me about installing a tankless in a home I recommend having a small tank wh on the discharge in line with the flow. You still get the unlimited hot water but avoid the cold water slugs common when throttling faucets below minimum flow to start the tankless. Obviously not feasable in a TT.

[Ralph12]

Check to see if the faucets have a "water saver" in them, these will keep it from lighting also remove and replace the pressure regulator

[alantbird]

YES on the flow. Ive had a few of these and they are very sensitive to flow.

[sonyamontana]

THANK YOU! I timed the flow out of the kitchen sink and it was slow. I cleaned out the faucet head and voila!, running hot water out of the kitchen sink now works! You all are amazing!

As well as the kitchen sink works, the shower still doesn't produce enough flow to kick on the hot water heater. I did my best to clean out the head and hose. Something to note about the shower - im not sure how well the mixer is working. I've tried operating it with only the hot water on, but the pressure is still low. I'm thinking of getting something like this: http://www.vintagetrailersupply.com/...-p/vts-593.htm. Do you think that would help increase the water pressure? What else should I consider?

Thanks again everyone- this forum is a life saver!