Hybrid home HVAC

[OVERKILL]

The province recently offered (it expires Friday) a time-limited program for select communities (including mine) to rebate $3,000 for a hybrid heat pump, or $4,500 for a Cold Climate hybrid heat pump system.

My old century home is 4 stories (including the basement) and we've been running a window shaker for years because I didn't opt for central air back when we had the new furnace installed.

I contacted them and had somebody come out and my furnace was new enough to work with the program and so today, after about 6 hours, I had a Cold Climate heat pump integrated into my HVAC system, which will handle heating duty above 1.5C. I may adjust that down, that's just where they set it. Below this temperature, it runs my gas furnace.

So, today, I'm heating with electricity. Tonight, I might be heating with gas, should be interesting. But, my wife will now be happy that we have central air, lol.

Unit that was installed was a mid-tier Carrier Performance series, 2-ton.

Anybody else looked at doing something like this?

 

[Zee09]

I have both hybrid oil combo and hybrid propane. Different houses.
One is a Lennox and the other a Bryant...because of my inexpensive electric I ran them hard this year.

Years before I ran them in auxiliary mode so I could pick straight oil-propane heating when fuel was cheaper years prior. Happy so far....

 

[Zee09]

The only thing that bothered me in hybrid mode was the long run times but I got used to it eventually.

 

[RhondaHonda]

What are summers like there? 2 tons will cool 3 stories above grade or is this just for a certain area? I’m a softy and need my AC!

 

[Rand]

What are summers like there? 2 tons will cool 3 stories above grade or is this just for a certain area? I’m a softy and need my AC!

They can be anything shorter season than down south.. anything from 70's to 90's.
I was there fishing one year and 4-5 of the days were mid-high 90's.. thats a bad fishing week.

Had quite a few cold showers with the cottage .7gal low flow shower head.

I'm more interested in the number crunching for natural gas price vs heat pump for heating.
The real massive benefit as mentioned is A/C in the summer.
I have amazingly cheap natural gas here(3.31/mcf but the 45$ connection fee blows.) last month was 64$ total bill
about 6mcf.

If I didnt need gas for the furnace I'd save 500+ connection fee. per year.
heat pump would easily be more eff. than my current trane AC 14 Seer?

Just dont know how much I'd need emergency heat. which would then be electric.

It would never make sense probably. I just detest unfair connection fees.

Its not so bad if the connection fee isnt 3/4 your yearly gas bill.

@OVERKILL
any stats on the HSPF of the heat pump also the seer rating... and what are natural gas and hydro prices?

 

[OVERKILL]

They can be anything shorter season than down south.. anything from 70's to 90's.
I was there fishing one year and 4-5 of the days were mid-high 90's.. thats a bad fishing week.

Had quite a few cold showers with the cottage .7gal low flow shower head.

I'm more interested in the number crunching for natural gas price vs heat pump for heating.
The real massive benefit as mentioned is A/C in the summer.
I have amazingly cheap natural gas here(3.31/mcf but the 45$ connection fee blows.) last month was 64$ total bill
about 6mcf.

If I didnt need gas for the furnace I'd save 500+ connection fee. per year.
heat pump would easily be more eff. than my current trane AC 14 Seer?

Just dont know how much I'd need emergency heat. which would then be electric.

It would never make sense probably. I just unfair connection fees.

Its not so bad if the connection fee isnt 3/4 your yearly gas bill.

@OVERKILL
any stats on the HSPF of the heat pump also the seer rating... and what are natural gas and hydro prices?

Up to 28.1 SEER and 13 HSPF.

Gas: I used 497 cubic meters last month, which was $304.65:

Electricity: I can lock in for a fixed-rate at $0.12/kWh if I desire, which I might do depending on how my usage in the next couple of months looks.

 

[Zee09]

I am just under 8 cents a kWh
so that's why I am running it and luckily we had a mild winter this year.

 

[Rand]

holy crap thats 17mcf.. i guess not that terrible for your location and house size.
(my gas bill for that would be around $110) even with the usd>cad seems over double.

Can you program the heat pump to not run during peak? or maybe use a schedule to bump the heat up from 5am-7am.. then taper off a few degrees for peak.

Your hydro seems pretty inexpensive.. I'd think you will save considerable... if you dont change settings much from previous ie keep the house hotter.

obv. for AC if you are running it when there was none before its going to raise the bill.. but those eff. numbers seem on the fantastic side of great.. esp compared to 10-20year old equipment.

 

[OVERKILL]

holy crap thats 17mcf.. i guess not that terrible for your location and house size.
(my gas bill for that would be around $110) even with the usd>cad seems over double.

Can you program the heat pump to not run during peak? or maybe use a schedule to bump the heat up from 5am-7am.. then taper off a few degrees for peak.

Your hydro seems pretty inexpensive.. I'd think you will save considerable... if you dont change settings much from previous ie keep the house hotter.

obv. for AC if you are running it when there was none before its going to raise the bill.. but those eff. numbers seem on the fantastic side of great.. esp compared to 10-20year old equipment.

I was running a massive window shaker, so while I had no central air, we did cool (most of) the downstairs. It required a slow-blow or it would throw a 15A fuse/breaker, big unit that drew a lot of power.

 

[Zee09]

@OVERKILL look out for this.

Heart surgery people tend to run cold and in hybrid mode I can keep the same warmness to my bones at 66 F. degrees compared to oil at 71 degrees F. and without the nasty early season oil smell even from a well maintained oil furnace.
I noticed this early on and without the heavy air oil creates.
Oil was big here forever but never again. Propane isn't anywhere as bad but the heat pump just seems to do better here as long as I am around 40 degrees or so. Last night was 36f and set at 66F I was fine..
Good luck and I suspect thermostat adjustments may be warranted.

 

[Cujet]

Excellent, I'm a huge fan of a well designed heat pump system.

Although the laws of thermodynamics and the Carnot cycle don't allow heat pumps to be equally effective at all temperatures, many modern heat pumps vary the compressor speed to "sandbag" the system a bit. Put another way, a 2 ton unit may have a 5 ton compressor that is de-rated to 2 tons during modest temps, with the compressor only being run to full speed under a certain outside temperature. At no time does the unit produce more than 24,000 BTU worth of heat. But performance does not suffer as much as a conventional single speed compressor might.

There is no magic here, we simply benefit from the design criteria. Also of note, SEER ratings that are "too good to be true" are exactly that. They are only achievable when there is a very minimal temperature differential. Such as 55 deg F outside and 60 deg F desired inside.

Here is a graph of what an oversized, variable speed compressor can achieve.

 

[SubieRubyRoo]

The only thing that bothered me in hybrid mode was the long run times but I got used to it eventually.

long run times in hybrid cooling mode is actually a benefit as it will dehumidify the air much better than an oversized unit that achieves the target temp much faster. On the heating side, longer runtimes are a benefit as well, as it will better raise the temps of the thermal mass, which is what determines the true comfort level. You can have hot air with cold surfaces that is very uncomfortable!

 

[Zee09]

long run times in hybrid cooling mode is actually a benefit as it will dehumidify the air much better than an oversized unit that achieves the target temp much faster. On the heating side, longer runtimes are a benefit as well, as it will better raise the temps of the thermal mass, which is what determines the true comfort level. You can have hot air with cold surfaces that is very uncomfortable!

Yup and it did-does but if you have mechanical sympathy or just outright cheap it takes some getting used to...

 

[OVERKILL]

@OVERKILL look out for this.

Heart surgery people tend to run cold and in hybrid mode I can keep the same warmness to my bones at 66 F. degrees compared to oil at 71 degrees F. and without the nasty early season oil smell even from a well maintained oil furnace.
I noticed this early on and without the heavy air oil creates.
Oil was big here forever but never again. Propane isn't anywhere as bad but the heat pump just seems to do better here as long as I am around 40 degrees or so. Last night was 36f and set at 66F I was fine..
Good luck and I suspect thermostat adjustments may be warranted.

I just changed the cutover point to -5C (it's currently -3C) and the heat pump is having no problem keeping the house warm.

Yeah, I remember that oil smell from out east as my dad had a triple heat setup with electric radiant as "last resort" and wood and oil as the primaries.

 

[OVERKILL]

long run times in hybrid cooling mode is actually a benefit as it will dehumidify the air much better than an oversized unit that achieves the target temp much faster. On the heating side, longer runtimes are a benefit as well, as it will better raise the temps of the thermal mass, which is what determines the true comfort level. You can have hot air with cold surfaces that is very uncomfortable!

Yeah, my gas furnace is huge, like 110,000BTU. It makes a lot of heat, which, when it's -30C is great, but also means it short cycles when it isn't super cold, even though it's multi-stage, even on low, it's still 55,000BTU, which means short run times when it's like -5C and above.

 

[SubieRubyRoo]

Yeah, my gas furnace is huge, like 110,000BTU. It makes a lot of heat, which, when it's -30C is great, but also means it short cycles when it isn't super cold, even though it's multi-stage, even on low, it's still 55,000BTU, which means short run times when it's like -5C and above.

My propane furnace somehow got sized at 100k BTU (installed in 1998), and when I did the calculations now I found it should have been about 60k BTU. It certainly warms the house VERY fast, but once it shuts off it almost immediately feels cold again within 10-15 minutes, and the furnace is usually on again within 20 minutes for another 3-5 minute heating cycle. Single stage, of course.

 

[OVERKILL]

My propane furnace somehow got sized at 100k BTU (installed in 1998), and when I did the calculations now I found it should have been about 60k BTU. It certainly warms the house VERY fast, but once it shuts off it almost immediately feels cold again within 10-15 minutes, and the furnace is usually on again within 20 minutes for another 3-5 minute heating cycle. Single stage, of course.

Yeah, mine only ever steps up to stage 2 when we get near -30C, otherwise, it never moves beyond the 1st heat stage.

 

[simple_gifts]

Yes, i was considering doing this with my new place and was going to post/ask about it after i collected some info.

My new place (condo) has an in unit Lennox Signature NG furnace and a roof top York A/C. The seller indicated the A/C was in working condition even though it is from 1989. (The condo was an old building conversion done in 1990-91) No reason to doubt this because there are other condo units with the exact same York although probably more than half of them have been replaced.

Since the York will need to be replaced soon, i was toying with the idea of just installing a H.P. and use the gas furnace as a backup or supplemental. I believe there is also a tax credit for installing a H.P. Here is the compelling motivation. The A/C is 5 stories up and will require a crane for replacement. I figure if I have to shell out the $$ for that, i might as well install something that might be less $$ to operate down the road (or immediately) We did not have much of a winter this year and perhaps a H.P might we the way to go. Any body have thoughts on this? How is the H.P. with aux furnace controlled? Two thermostats?

I have 1650 sq feet and 12" ceilings with only 1 exterior facing wall. The inspector said the A/C is a 3 ton unit. Would anyone else consider doing this?

-Thomas

 

[brianl703]

Why are they setting a "cold climate" heatpump to only run above 1.5C/35F?

It's stupid to even do that with a regular heatpump.

 

[OVERKILL]

Yes, i was considering doing this with my new place and was going to post/ask about it after i collected some info.

My new place (condo) has an in unit Lennox Signature NG furnace and a roof top York A/C. The seller indicated the A/C was in working condition even though it is from 1989. (The condo was an old building conversion done in 1990-91) No reason to doubt this because there are other condo units with the exact same York although probably more than half of them have been replaced.

Since the York will need to be replaced soon, i was toying with the idea of just installing a H.P. and use the gas furnace as a backup or supplemental. I believe there is also a tax credit for installing a H.P. Here is the compelling motivation. The A/C is 5 stories up and will require a crane for replacement. I figure if I have to shell out the $$ for that, i might as well install something that might be less $$ to operate down the road (or immediately) We did not have much of a winter this year and perhaps a H.P might we the way to go. Any body have thoughts on this? How is the H.P. with aux furnace controlled? Two thermostats?

I have 1650 sq feet and 12" ceilings with only 1 exterior facing wall. The inspector said the A/C is a 3 ton unit. Would anyone else consider doing this?

-Thomas

It's all managed with a common thermostat, you set the cutover temperature.