Re: furnace floor heat
Reply #4 –
Yahoo Message Number: 113983
Here's a quick primer on HVAC as well as a couple of quick troubleshooting issues. My guess is that our coaches are somewhat similar although I can't guarantee it:
HVAC in General:
Our coach has 3 rooftop Airconditioner/Heatpumps and Aquahot as well as in floor heating in the kitchen.
Thermostat:
We have a coleman thermostat that is linked to our ROOFTOP HVAC units. Inside each unit is a "Zone Board" that has electronics that control the zones (we have 3, one for each rooftop unit). The boards take a signal from the thermostat and send it either to the Aquahot (if you choose GAS HEAT) or to the HVAC Unit in Heat Pump Mode (If you choose ELEC HEAT). If you choose GAS HEAT, the Aquahot takes over and controls the pumps that circulate hot coolant (heated by the Aquahot) to your zones via relays just like a hot water heat system in a house). You determine (by zone) whether you want to have your heat come from the rooftop AC or from the Aquahot by cycling your thermostat from zone to zone and then switching from Heat Gas to Heat Elec via the "MODE" button. This can only be done when your thermostat is set to HEAT (instead of OFF or COOL).
If you choose HEAT ELEC - the boards that are in the Rooftop HVAC units in each zone will tell the rooftop unit to start in "Heat Pump" mode and you will feel warm air from your ceiling vents (that cold air comes from when you have the Thermostat set to COOL.
If you choose HEAT GAS - the boards in in each rooftop HVAC unit will signal the Heat Pump in the Rooftop Units NOT to turn on and will signal the Aquahot in the basement to fire (which sounds like a little tiny jet engine - with hot exhaust coming from the Aquahot) and take responsibility for heating, as descibed above, the Aquahot then "tells" the zone pump to pump hot water and the exchanger fan to start up in each zone. A sensor in each zone reports back to the Thermostat whether its warm or cool enough and the thermostat tells the board whether to tell the Aquahot to turn off the pump for that zone. If all zones calling for heat are warm enough, all zone pumps shut off and the Aquahot powers down.
Heating:
- Aquahot. Your Aquahot system heats your hot water AND pumps hot water through exchangers in your floor registers. We have floor registers in the front below the dash, in the middle under the kitchen sink and in the bathroom and in the back under the rear closet that usually houses a washer/dryer (which in our case is a closet).
- Aquahot can be run using "Electric" or "Diesel". Electric is enough to heat water for dishes and using the sink, but won't provide sufficient hot water for a shower or to the air exchangers for heat. You have to have "Diesel" on your Aquahot panel set to "ON" and your Thermostat set to GAS - HEAT for each zone that you want to operate.
Troubleshooting Aquahot - if you aren't getting heat from your registers:
- Check to see you have Diesel Burner selected on your aquahot panel (located next to the thermostat on the panel outside the Lavatory in our coach).
- Check (listen) to see if your Diesel Burner fires (it should and you should hear the fans whiring in your floor registers) and feel warm air. It won't be a flood of warm air, just a gentle amount of warm air. If you turn on "Diesel Burner" to enable your Aquahot AND shut off "Electric" and run hot water you should also hear the Aquahot fire up. This is the acid test to determine if your Aquahot is working at all, more about this in troubleshooting below.
- If you aren't getting heat, and dont hear the diesel burner fire, first check to see if the problem is confined to only 1 zone or all of your zones (by setting all zones to GAS - HEAT). If its just 1 zone, often switching off the thermostat and turning it back on, or switching from GAS HEAT to ELEC HEAT and back to GAS HEAT will clear the fault. Failing that you can look at whether there is a zone problem with your AquaHot (evidenced by a red light on your Aquahot panel located in the bay next to the aquahot itself), If the Aquahot zone panel is all green - including the "pump" for the zone you are trying to get working, then you may have a problem with the "board" in your HVAC unit that takes the signal from the thermostat and interprets whether you want GAS HEAT or ELEC HEAT. I've had 3 "boards" go out in the 3 years that I've owned the coach. They are VERY sensitive to power fluctuations and tend to fail without warning. Replacing them is easy if you are at all handy with a screw driver and know how to get to them - up through the ceiling by removing the ceiling panels. Lots of people don't like to do this, but any competent RV tech can probably do it.
- If your Diesel Burner does not fire on any zones its unlikely that all three "boards" in the HVAC units will fail simultaneously - check the "status" panel on your diesel burner - likely located in the bay right next to the aquahot and look for red lights. Common problems here are blown fuses, circuit breaker, low coolant (which you can top off in the Diesel burner with a coolant available at RV stores) or occasionally a broken low coolant sensor (which basically locks out the burner because of an erroneous signal from the broken sensor). An Aquahot tech can replace the sensor (they typically fail at some point) and if you are lucky, they can tell you how to by pass the sensor until they can get to you so you have heat and hot water.
- Basically, if you have hot water for showers you should also have Gas Heat - unless there's a problem with the zone pumps, the HVAC boards or the Thermostat itself.
HVAC Heat -
Basically, if your thermostat works and your HVAC unit works - you will have ELEC HEAT as well as A/C. If the HVAC board dies, its been my experience that you will have A/C but not Heat (either GAS or ELEC) for that zone, but your other zones should work fine.
Hope this helps.
Jim and Jona Seifert
2007 Country Coach Intrigue Ovation 530 42'
Coach #12150
525 Cat C13 Allison 6spd
Toads: 2014 Ford F150 / 2007 Toyota FJ Cruiser w/ REMCO DS Disconnect.
Airforce 1 Brake system
Blue Ox Aventa II Towbar
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