We have a Hydro-Flame 8232 furnace in our '89 Holiday Rambler. When we bought it a couple of months ago, the furnace didn't work. The previous owners said they never used the furnace (believable, as it didn't work). It basically did nothing when the thermostat called for heat. I pulled the unit out and took it home from the campground to see what the problem was. It looked like it had never been used - the heat exchanger hadn't changed color yet like they do after being used a few times.
I found the circuit breaker's reset button and pushed it. It clicked. I hooked it up to a battery and an LP tank (w/ regulator) and the unit cycled on, ignited, and blew heat. When I disconnected the jumper between the thermostat wires, the valve closed and the fan ran a while to cool the unit down. I noticed there was still quite a bit of heat in the heat exchanger area. I took the furnace back to the trailer, installed it, and tested it. It worked fine. Later, I raised the thermostat, and nothing happened. I pulled the front cover and reset the unit, flipped the thermostat switch to on, and the unit ran fine.
Here's what I think's happening. I believe the ductwork is too restrictive and doesn't allow the unit to blow most of the heat out of the furnace after a heating cycle. I think this is the case because the circuit breaker never trips when the unit is firing... only after the blower has shut off. The circuit breaker is located in the heat exchanger area and would likely get hot from the heat building up from the still hot exchanger; it's a simple thermal circuit breaker.
There's nothing I can do to relieve the restrictive ductwork. It's 4" round flex tubing in the floor. I'd like to do the following. 1) have the blower run 'til the heat exchanger area is much cooler... like a home furnace and 2) reduce the heat output. I'm sure a thermostat like used to cool attics could be used to trigger a relay to keep the fan on. Can the orifice be changed to a slightly smaller one? 2500 watts worth of elec. heaters will keep this trailer warm in temps in the upper 20's. I don't really see the need to have quite this much heat. I'd think reducing it down to around 24-25,000 BTU's would be fine.
I'm interested in any feedback, experiences, or suggestions on dealing with this furnace. Thanks.
1978 MCI MC-8 ...Conversion in progress
1989 Holiday Rambler Imperial 29
1998 Chevy Express 3500 Conversion Van
I believe there is other items that change between BTU outputs. Many furnaces have different motors.
Suggest you check the duct work for places that it has collapsed causing in-sufficient air to move through.
Another item to check for is the anticipator setting. This will not cause it to shut down funny, but would when properly adjusted reduce the furnace run time. Furnace should cycle about 6 times per hour.
I would try to fix problem. Some modifications could cause more problems.
From what I can tell from the rather sparse manual, the heat exchanger is common between a couple of outputs. I'll have to see if I can find the parts manual (good luck on that!) for mine and a lower capacity furnace to see what parts are the same.
I guess I just need to check the current draw next time I'm there. I mainly don't like the fact that so much heat stays in the furnace when the fan turns off. I know that it takes more battery power to run the fan longer, but it's a waste of propane. Plus, we don't rely on the battery (we generally plug in to AC power).
As to my second question, can I replace the orifice in the burner with a smaller one? The current furnace is greatly oversized for our trailer. I'm thinking it should be relatively easy... like changing the orifices on a grill to change from LP to natural gas. Any suggestions on this? Thanks.