Furnance Issues

[bjboles]

Journey39n,
Great tip. I think what I will do next time it's predicted to get down to 50-60 at night is to stay ahead of it. If the inside temp is 74 degrees before we go to bed, I will set the heat pump to like 68-70 this way it's all set and kick in when needed.

So only one compressor will kick in if you try to cool the coach down 1-2 degrees? I did not know that.

[NeilV]

Originally Posted by Morich

I may have created some confusion on the way I drew the airflow on my previous snip as it is not as difficult as I may have made it appear. There is no problem, at least on this furnace, with the blower putting too much pressure on the sail switch.

One of the big features of all current model furnaces, is that the combustion air where we find the CO and hazardous fumes is ALWAYS kept separated from the room air which we breathe. Basic design, so that we don't get gassed?

But my drawing seems to have confused folks who have not actually looked at the airflow, so I have found a different exploded drawing which is a bit more clear and maybe I can show it better here.

The intake to the combustion air seems to be on top here and if we follow the red line, it goes in, across the smaller squirrel cage fan blade, into and through the combustion air chamber and then back out the exhaust. Item 36 is sandwiched and sealed inside item 37 which keeps any air from the burners from entering the room air which is on the other side of this seal where I've drawn the green lines.

Item 44 is the sail switch and it is shown as being in the larger chamber where the room air flows. Since the room air fan and combustion air fan are on the same shaft, it is assumed that they both move together. The heated room air is drawn in the RV intake vents, across the top of the heated furnace heat exchanger and back out into the room. No mixing with the gases in the combustion airflow!

It may not be true on ALL RV furnaces but on this specific design, the room air is where the big blower fan is located and the sail switch is in that airflow,
So damage to the sail switch is not likely if we use a blower on the combustion air.

I agree that it may be different on other furnaces but then designing it to put the electronics and switch in the heated air of the combustion air would seem to be a pretty poor idea.

The devil is often in the details and we do need to look close to sort out the solutions.

I've seen them both ways. On the combustion side the sail switch is usually on the intake and not the exhaust so usually no worries about combustion gases impacting the switch. Even with the sail switch in the room blower side on units with a common shaft turning both the combustion and room blowers, you still want to be careful to not spin the blower backwards using too high a velocity air stream.

Look before you leap and know which one your dealing with. Better to be safe rather than that other thing.

[Morich]

Yes, totally wrong to go about thing as if all Rv are made the same but since we are only speaking of one specific Rv , It cuts confusion if we don't try to talk about things that are not true on that RV, doesn't it?

Too many nitpickers want to throw in junk that doesn't mean anything on the question!