DIY Message Boards
HVAC Issues: Furnace and A/C compatability

This topic can be found at:
http://boards.diynetwork.com/eve/forums/a/tpc/f/9221916776/m/1383996077

May 26, 2013, 12:08 PM
GardenSprite
HVAC Issues: Furnace and A/C compatability
Frodo, again thanks for the advice.

This is going to be an interesting experience. As Nona has found, some of these companies are very particular in what they will or won't do, and what areas they will or won't service. In this region, some of them won't go more than 25 or so miles, even though they charge $85 for a service charge. I suppose it's an issue of the extra drive time decreasing the number of clients they can serve.

But I will add a pressure test to the contract; they'll probably charge an arm and a leg for it!

I'll also ask for a quote on balancing. If I'm going to shell out about $8k (+/-), it's worth it to pay extra to make sure I get my money's worth, even if I have to get quotes from several until I find one that doesn't resist the tests you suggest.

And even if they do, they'll wonder where I'm getting all this good info. Can I tell them I have a friend in the business? Smile

Is this the kind of flexible duct work you refer to?

http://www.homedepot.com/Heati...10053&searchNav=true

Apparently the largest diameter is 12". I assume that would be an inside diameter?

If the diameter of the duct is smaller, is the air forced through at a higher rate, or is it restricted? Is the duct diameter a function of the capacity of the system, i.e., tonnage capacity? I'm assuming that residential duct diameter is significantly less than commercial duct diameter.

It also looks as though the insulation is fiberglass, with a nominal outside wrap. Wouldn't this be subject to puncture, not that I'm going to go around poking holes, but it also looks as though it could be easily chewed through. Is this why you wrote the mice love it?

Periodically my phone lines have to be replaced; the tech guys said the squirrels love to chew on the insulation.

I can see that it could also be a dust/germ/whatever collector. Does a flex duct have to be cleaned? Actually, it looks like a real piece of junk, probably from China, which in my opinion makes it a hazard just for that reason.

I'm familiar with the soapy water test; used it to find leaks in tires. (I'll follow them around with my water bottle! Wink

Thanks again for the tips; I really do appreciate it.

And off topic, how is your mother today?