propane upflow unit

[rasit]

Anybody using a regular house furnace to heat. I am considering a used 75K unit for my 30x40 with 13' ceiling. Was thinking about running a 12" round duct 10' high for the length of the garage with registers pointed down at 45degree angles. Kinda industrial lookin.... whadaya think????

 

[chevelle67]

It will work but if its a condensing furnace the space temp must be above freezing at all time. Can not tell you how many cracked secondary heat exchangers we have found because people turn the heat off but fail to realize that the secondary is full of water.

 

[rasit]

Thanks for the reply, I didn't know that. Guess that's out of the question......

 

[lametec]

....the secondary is full of water.

Full of water? If the condensate drain isn't clogged, I don't see how this could be?

The secondary heat exchanger is basically a radiator, where the gases are cooled to a temperature low enough for the water in them to condense. This causes drops of water to form, which will be blown out of the heat exchanger by the induced air flow. I wouldn't be surprised if they're even mounted in such a way that gravity would make the water flow towards the exit once the inducer fan stops.

 

[FXR]

Would one really need a trap in the condensation line for a garage?

 

[HoosierBuddy]

Note to the OP...

Is it a condensing furnace you are considering?

That would be a 90+ furnace that utilizes a PVC vent rather than a metal flue. It's quite possible a used furnace is not that.

Phil

 

[chevelle67]

Even with a proper drain there is still water in a secondary HE. In a perfect world the HE would drain totally but the world is not perfect and many crack when they are in freezing temps.

 

[lametec]

True. I still don't see how there can be a big enough collection of water to cause cracking, though. Not saying it doesn't happen, just that I can't see how a properly functioning drain would allow that much standing water in there.

Now if the furnace wasn't mounted level, with it leaning away from the drain side, I could see it.

Just trying to learn.

 

[chevelle67]

Some tend to crack more than others, Carriers being the most frequent. Sorry if my other post sound`s sharp wasn`t meant to be.

 

[lametec]

Carrier was sued over their heat exchangers, though. http://www.lieffcabraser.com/furnace.htm

This is a similar issue to freeze cracking cylinders on my Seadoo PWCs. Normally it shouldn't be an issue because there are drain hoses on the low point of the sleeves , but if the hose plugs it could happen.

 

[chevelle67]

Even The recalled updated HE crack. Have a happy Halloween

 

[lametec]

You too!

 

[rasit]

Note to the OP...

Is it a condensing furnace you are considering?

That would be a 90+ furnace that utilizes a PVC vent rather than a metal flue. It's quite possible a used furnace is not that.

Phil

No, the unit I was looking at was 80% with metal flue. Let's say I get a good thermostat and keep the temp down around 40 during the week when I'm not in there much, make sure unit is level and any drains are clear, is it worth the risk or should I just bite the bullet on a Modine or similar as suggested throughout the forum?

 

[lametec]

An 80% furnace won't have any drains (other than for A/C). Only 90%+ furnaces are condensing furnaces.

An 80% furnace won't have any issues sitting in a cold garage.

 

[rasit]

thanks for the info....