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[hondaracer2oo4]

Hello everyone, I have been very very busy for the past few months and haven't been around this site much. I have a question for those using there oil burner or gas burner as back up through the FHA system. I installed my system when I bought the house and have never used the oil burner since install. Recently I replaced the flue pipe for the oil burner since it was not in the best condition as well as vacuumed out the inside of the furnace. I then fired the furnace up to give it a little exercise to make sure it was working correctly. What I noticed that I had not thought about was the fact that the water to air hx had 60 degree water in it which was effectively cooling the hot air blowing out of the furnace way way down. The water in the HX did start to heat up, rose about 20 degrees in two minutes. At that point I shut it down since everything was  working correctly and figured I would research more on what other peoples experience is running there burner through the hx. I assume that I would need to shut down the pump or isolate the hx from the loop if I was going to use the burner as a back up or I would never be able to heat up the water in the hx. Once the water gets up to temp in the hx will it stay up there for a long while so that the next time the burner fires it won't have to heat the water back up again in order to get warm air out of the registers?

[slimjim]

you should definitely  shut the circ off this time of year but leave it on below freezing temps. NEVER close ball valves on both sides of the heat exchanger because if you heat up the exchanger it will build pressure and may pop it.

[hondaracer2oo4]

The pump is off for the non heating season. My question is pointed toward during the heating season though. If I had to shut down the boiler I would not be able to keep circulating water because it would flow through the hx and  cool down the air leaving the fha inside never allowing me to get warm air from my vents. But if I shut down the pump I run the risk of freezing me lines. How do other people get around this issue?

[RSI]

It will take a bit to warm up the inside of the oil burner too. If you only occasionally need the backup heat, it will just take a little more oil to heat the house even with the pump running. As the water temp in the OWB rises, the heat exchanger will absorb less heat. If you have the blower running, it will slowly keep heating the house after the oil burner shuts off.

If you want to be able to the oil fairly often, you could just wire in a relay to turn the pump off while the oil burner is running but come back on once it shuts down.

[slimjim]

I use a simple break on rise honeywell strap on aqua stat on the incoming wood boiler line, bring the B-1 or burner power wire from the oil burner to the R terminal and back to B-1 from the B terminal on the aqua stat, this kills the oil burner whenever the wood boiler is above setpoint.

[hondaracer2oo4]

Thanks for the suggestions. I like the relay to cut the owb pump off when the oil burner is running. That should solve the issue with keeping the lines from freezing up. I don't plan to use the oil much but I would do need it to be a reliable backup since my wife is sometimes home for extended periods while I  stuck at work. I need to make it work so that if she has an issue with the owb then she can just turn up the oil thermostat and everything will change over. Thanks again!