Community Forums

pointrow · 07-16-2017, 11:26 AM

AH 400. Electric heats water ok but diesel burner kicks out after 4-5min. All green lights on panel. Hoses are warm and cold as should be. Tried heat and kicks out after 4-5 min also. I can hear the stir pump so ruled that out.
Any ideas? In NW ONTARIO so service will be slim.
THANKS
POINTROW

Mr_D · 07-16-2017, 11:35 AM

So, you aren't getting any heat or hot water since the system run time is so short?

pointrow · 07-16-2017, 11:42 AM

The electric seems to work for heating water.
Thanks
Pointrow

chuckster52 · 07-16-2017, 01:11 PM

Quote:

Originally Posted by pointrow

AH 400. Electric heats water ok but diesel burner kicks out after 4-5min. All green lights on panel. Hoses are warm and cold as should be. Tried heat and kicks out after 4-5 min also. I can hear the stir pump so ruled that out.
Any ideas? In NW ONTARIO so service will be slim.
THANKS
POINTROW

sounds like a dirty sight glass for the burner....may have soot on it

Spk64 · 07-16-2017, 04:03 PM

Here is a typical cycle for the diesel burner.
1. Switch on and assume Tstat is calling for heat.
- diesel burner status light should be on
2. Blower Motor starts running to prime the fuel pump and start the flow of air.
3. After slight delay 15-20 seconds and flame sensor seeing no flame.
4. Fuel solenoid opens and coil fires sparking to ignite the fuel.
5. If the flame sensor sees the flame coil shuts off and boiler runs like normal until it reaches temp.
- If flame sensor does not see a flame then fuel and coil is shut off and the blower motor will run in purge mode for 3-4 minutes.

So with this sequence your flame sensor could be the problem or it could be the fuel or coil. Determining which takes more troubleshooting.
I had similar problems and ended up being a bad Webasto Controller.

Cat320 · 07-16-2017, 07:39 PM

Here is a link for the AH only forum:

Activity Stream - RV Hydronic Heater Forum

luckyd · 07-16-2017, 09:59 PM

First (and cheapest) check your mixing valve.

Crabby Mike · 07-17-2017, 10:18 AM

How recently has your Aquahot been serviced? I've learned the hard way that these units need to be serviced regularly (annual if possible), and more importantly, used often. It doesn't help you now, but it's a good idea to fire up the unit every couple of months at least, to avoid gumming-up in the fuel system, sticking check valves, etc. Personally I'm betting on a clogged burner tip, but your symptoms could be caused by a number of things, but all in the diesel burner system.

And I assume that your diesel tank is above 1/4 full?

Steve COH · 07-17-2017, 10:27 AM

The upper limit thermostat could be acting up, since everything up to that point seems to work.

Its easy to bypass and check. Aquahot customer service can describe for you.

Spk64 · 07-17-2017, 10:34 AM

Quote:

Originally Posted by Steve COH

The upper limit thermostat could be acting up, since everything up to that point seems to work.

Its easy to bypass and check. Aquahot customer service can describe for you.

Forgot about the high limit T-Stat. Yes it is wired in series to the coil and Fuel solenoid. So if it is failed then coil or fuel will not be working.

pointrow · 07-17-2017, 01:33 PM

Thanks for the ideas. Unit was serviced in the last year. Fuel is above 1/2.
Probably won't dig into it till I get home in sept because we can limp along on electric till then.

Thanks
Pointrow