[pdbrantley]

So... I have a ranch style home built in late '60s. My HVAC equipment, water heater, and dryer are in an unfinished, uninsulated garage area in my basement. I've done my best to airseal this area, but it's still drafty, and this is making the half of the house above noticably colder.

The house is total gas with only a 100 AMP service. This is our first winter here (Alabama), and I am not liking the trend of my recent gas bills. So I've decided to swap out my gas furnace and AC (80% and 10 SEER) with a new piggkyback heat pump setup.

I'm doing this so I can cut back on some of my gas use in the winter when prices are higher, and have a buffer for rising prices of fossil fuels. I'm also in the process of air sealing and adding extra blown insulation to the attic. With an eye towards sealing and insulating my homes "envelope."

My contractor quoted me a 14 SEER heat pump and 80% furnace. I originally wanted a 16 SEER unit, but he talked me out of it. Since my house is older and it gets so hot and humid here, I likely wouldn't use a lower power cooling mode very often, and since my electric bills are that bad it wouldn't be worth the cost. Or so he has convinced me.

But I think I want to get back to him and request a 96% gas furnace. Other than the extra 16%, I think the main benefit here is that it will draw combustion air from outside. Hopefully keeping that garage area and the house above it a bit warmer.

But I'd like to get an idea of what that would involve from you guys before I get back with my contractor. My main concern is what will have to be done with the vent for the water heater. From what I've read I think it should be ok???

I'd like to have the PVC run along to the exterior wall about three feet to the left (from the outside) of the laundry vent. And then leave the water heater in place with its current configuration.

I really want to avoid getting a power vented water heater for what should be obvious reasons.

I'll post some pictures showing how everything is setup... In 6 more posts.

 

[pdbrantley]

Right now it costs a lot more to run heat than AC. The electric bills have never been bad here, even in the middle of summer. I am on the north side of a slope and have some large oaks shading the south side of my house. We also have a whole house fan we use a lot during spring and fall. So summer energy bills aren't really a concern for me.

And do you think it will change the humidity that much? I realize high humiditycan make it feel colder, and I definitely don't want moisture or mold issues, but don't mind higher humidity otherwise. I actually had a bypass humidifier installed because the dry gas heat was very uncomfortable. I plan on having it removed when the new unit is installed.

 

[pdbrantley]

I see what you are saying. I am new to this gas thing. This is my first home with a furnace instead of an air handler. How much should I expect this thing to run. Maybe it's not as bad as I thought, or I have some problems elsewhere.

The last few days it's be in the 30-40s range. I keep the house at 67 when occupied, 58, when empty, and 65 at night. And I've averaged 6 hours of heat use a day.

I know a higher SEER heat pump will help with electricity bills in the summer. Will it also prevent the AUX heat from kicking on as much in the winter?

 

[pdbrantley]

I'd prefer not to have such a range. Is it bad with gas too? Like what should I dial it into?

 

[pdbrantley]

Yes! My previous place (rental) had one and it was beautiful!

 

[pdbrantley]

Haha! Thanks, that was really helpful. I bookmarked so I can refer to it when working with contractors in the future too.

This guy is actually a family contact. He put in a high efficiency unit (like 17.5 seer I think) for my uncle about a year ago. That's why I was confused when he recommended against a 16 SEER heat pump. Although that could have more to do with the financing I was using?

That's why I wanted to come here and talk with y'all before I brought it back up with him. I'd rather come off as an idiot to semi-anonymous folk on the internet.

 

[pdbrantley]

We prefer "An Educated Consumer"

Yeah, I know just enough to be dangerous. From a potential contractor's point of view at least...

Hard to say for sure over the internet. If the W/H and clothes dryer share the same air source, it wouldn't be difficult envision the w/h flue backdrafting during dryer operation with the envelope tightened.

They do share the same air source. They are both in the unfinished garage. About 7000 cubic foot, with the aforementioned garage door, two single pane windows with glass storm windows. There is a CO detector down there, and it never went off in the summer when the water heater would have been running without the furnace draft inducer, and at the same time as the dryer. But I do realize that cold temperatures change how that flue works, and in ways that I don't understand.

 

[pdbrantley]

And pictures

 

[pdbrantley]

Tape on exhaust ducts are a huge RED flag in my book.

Thanks I didn't realize that. It was put on when the humidifier was installed. I think that section of the vent had to be moved to get access. Should it be removed?

 

[pdbrantley]

J,

Natural gas prices here are around $1.93/THERM in the winter.

I'm not as confident on the electric prices, but it think they stay around .11 ~ .13/KWH.

The contractor did not do an energy calculation, but I will be sure to ask about this.

Okay, so earlier when I said I would rather look like an idiot in front of people on the internet. Well here goes that thing happening now...

I don't really know how this furnace is supposed to work. But I don't think it's supposed to be doing what it is doing. I think it's short cycling. I turned it on this morning and times it. Here is what it.

Outdoor temp: 30f
Initial Temp: 65
Thermostat set to: 67


m:s
T:00:00 Thermostat is changed
T:00:02 Draft inducer turns on
T:00:54 Electric ignighter heats up
T:01:10 Gas burners and cage fan turn on
T:11:06 Gas burners turns off
Thermostat reads 66 and is still calling for heat.
T:13:46 Blower turns off
T:13:48 Cycle starts again

This is short cycling and isn't supposed to happen right? May this be part of the reason for my high gas bills?

 

[pdbrantley]

I put in a service request though our home warranty company. They sent a service tech out who looked at the unit. It did short cycle while he was there. He checked the overheating switch (or whatever it's called) and said it was still closed. So he diagnosed it as a bad control board.

Now I'm trying to figure out whether it makes more sense to get the board swapped and keep my current equipment or to go ahead and replace the equipment and get a heat pump so I can also save on my cooling bills as well.

Here's my weather and runtimes for the last days. The average set temp was around 67 for this time. And never going outside 65-69

Thurs | 45/35f | 5 hours heat

Fri | 48/27 | 5

Sat | 52/27 | 4.5

Sun | 55/32 | 4

Mon | 61/36 | 3.5

I don't know if that will help at all. I'm just trying to get an idea of what I should be seeing from a correctly functioning 80% furnace in a moderately well insulated home 1800sqrft on a basement.