Is there REALLY no system capable of 15,000 BTU/hr with a max current draw of less than 22 amps?
Hi Folks
Need your collective help again.
For those of you not sick of me yet. My situation is I am on a strata council trying to blaze a path for owners to electrify their home heat and hot water which is currently gas.
Got the Strata Bylaw in Place
Got an Engineer to sign off on the max current allowable at 240V that everyone can use without forcing anyone to go without OR requiring a feed upgrade. ~22 amps max current.
Got some solid heat loss measurement based on gas use. Even had some convenient -6C weather to reality check it against. In my case I am looking at a 15,000 BTU/hr system.
Now I just need to spec some equipment. Was hoping to keep it simple and swap out the forced air gas furnace with a Heat Pump powered air handler to handle the ducted lower portion of the townhouse and a ducted ceiling unit to handle the upstairs bedrooms. Add some air returns upstairs and call it a done.
Called two local contractors and I am quickly told there is NOTHING that small.
Being the skeptical type, I had a look at Mitsubishi’s site, they have a
PVFY-P12NAMU-E1 that is rated for 12,000 BTU – I’m thinking this would maybe be sufficient for the forced air portion of the house
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_PVFY-P12NAMU-E1_en.pdf
Then use maybe one of these PEFY-P06NMAU-E4 to duct air to the upstairs bedrooms? Just looking at the rating I feel like 6000 BTU/hr would be more than enough.
PEFY-P06NMAU-E4
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_PEFY-P06NMAU-E4_en.pdf
Then power them all with a MXZ-2C20NA3 capable of support 2 zones, which has a MCA of only 17 amps (the 24 variant has a MCA 22 amps, still possibly workable).
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_MXZ-3C24NA3_en.pdf
Am I grossly oversimplifying this?
Also would greatly appreciate it if anyone can recommend a well informed contractor in the Greater Vancouver area.
Or is my best bet to drop $2k on a design and equipment specification and then find someone who is willing to just install what I tell them to?
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Replies
Why not contact Corbett Lunsford with Home Performance TV? he has a Youtube channel and does consulting. If he can't help you I'm sure he could recommend someone.
https://www.youtube.com/@HomePerformance
What exactly do you have in the place? How much of the unit is the furnace currently heating and how large is it?
This might be in the ballpark:
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_SVZ-KP12NA_SUZ-KA12NAHZ_en.pdf
There is the 18k btu unit which does almost 2 tons of heat as well:
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_SVZ-KP18NA_SUZ-KA18NAHZ_en.pdf
These would be a direct swap for a standard furnace. Provided the original gas unit was oversized as most likely the case, the ducting should be more than enough for a right sized heat pump.
In either case the MCA is bellow the 22A limit.
If I remember correctly your climate is not that cold, in which case you can probably even use the 18k non hyper heat unit. A bit cheaper and much lower MCA.
https://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006\M_SUBMITTAL_SVZ-KP18NA_SUZ-KA18NA2_en.pdf
Exactly, what’s the problem with the 12kbtu hyper heat?
Why do the bedrooms need a separate ducted system if they’re currently being heated with a furnace?
The upstairs bedrooms are currently heated with baseboards, though heat comming up through the floor and stairs keeps them fairly close in temperature.
Then in the summer they can get much hotter than the downstairs.
Does HyperHeat offer other advantages besides low temperature performance?
Energy efficiency?
Turn down?
The advantage is the high capacity and efficiency at low temps. They’re less efficient overall but probably not a noticeable amount.
The townhouse is 1800SF in total, For the upstairs I am looking to heat about 500 SF (I'm excluding the hallway and shared bathroom.) Upstairs bedrooms have baseboard heaters, but the furnace keeps them within 2C (3.5F) of the downstairs. In the summer though, the upstairs notably hotter than the lower floors.
My family have indicated they would like to be able to shut their doors for privacy and still get heat in the winter. Hence why I would like to run ducts to each of the 3 upstair bedrooms.
I've attached some screen capture grabs of the sketch up drawing I have of it.
Vancouver has a mild climate. The record low is -15C, 99.6% is -7C and 99% is -4.5C.
Not a whole lot of solar heat gain in the winter though. Cooling degree days are about 1/5th of the heating degree days.
Thank you for the links. These do look like great options. I assume they are single zone only? I would need to either figure out how to extend ducting or get a seperate system to heat/cool the upstairs?
I'm a little confused as to how the PVFY-P12NAMU-E1 units relate to these are any of these compatible with multizone outside units?
Edit: Replaced the PDF's with JPG's. But the site really makes them hard to read. Tried posting the ducting diagrams as PDF's to allow a bit more resolution.
Those files didn't export properly. Try maybe as JPG.
I believe the PVFY is a commercial unit. The SVZ high static multi position, PEAD mid static and SEZ low static are the residential ducted units. You can connect an SVZ to a multi zone MXZ but only a single one, the other heads have to be either wall mount or PEAD/SEZ.
In your case you have a couple of options.
The simplest and cheapest is to replace the furnace with a right sized SVZ. By right sized I mean designed for 99%. Keep the existing baseboard in the bedrooms, in a townhouse, the cost of running those will never pay for anything else.
Once this is in, you can look at adding ducting to feed the 2nd floor down the road. You don't need to find all that much space, each bed is about a 5" flex and maybe an 8" flex for the return in the hallway. It is more disruptive, so best done doing a reno.
Next simplest option is to go for a two zone MXZ-2C20 with an SVZ to replace the furnace and a wall mount in the hallway on the 2nd floor, keep the baseboards. This gives you cooling upstairs plus almost all of the heat is now handled the heat pump. You'll have to keep bedrooms doors open through if you want cooling, but since the baseboards are there, they can be closed at night time for heat. Since the cooling season is very short, this is probably a reasonable compromise. I believe a 2C20 can be paired with an 18kSVZ and a 9K wall mount but check the combination table. The hyper heat multi zone seems to have better specs but you can probably go for the 3C24 non-hyper heat as well.
A 2nd ducted unit for the bedrooms is way more work and cost than ducting to the furnace. Also most likely the installer will want to put the unit into the attic which is the last thing you want.
Generally a hyper heat unit should be more efficient but on the Mitsubishi lineup, the non-hyper heats tend to get slightly better COP. The difference is small, so I would look for instead a better matched setup. Also check the NEEP site ( https://ashp.neep.org/#!/ ) for modulation range, lot of the multi splits tend to minimal turn down.
If you do eventually go fully ducted, you can take out the baseboards in the bedrooms which will free up some electrical service capacity. This should be enough to put in a medium sized EV charger down the road.
ok, I think I fixed the attachements. Hopefully the PDF's work this time. The JPG's do post, but the heavy compression they use make them a little hard to read.
I see your point about installing the second ducted unit and the baseboards. I'll check the power calcs and see what options there are. I still probably need to get rid of them. The Furnace room also has a gas fired hot water heater. If I replace that with a HP Hot water heater, I can repurpose the chimney to get a duct to the master bedroom. For the kids bedrooms there are a few options, would have to build some bulkheads I imagine.
I assume it would be a good idea to get some professional help to ensure the ducts don't mess up the airflow?
Fujitsu "mid-static" unit: 18RGLXD (https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/submittal-sheets/current/18RGLXD-2020A.pdf)
18 amp MCA. I have it in my house. It's exceptional.
Can it fit where you need it to fit? These units are not similarly shaped to conventional air handlers.
A much lower power version of that is what I would like to heat my bedrooms.
15,000 BTU is 4.4 kW. 22 Amps is 4.8 kW at 220V. So you're looking at COP less than 1. You should be able to get at least 2.0 at -6C. Even running 100% resistance heat you should be OK.
Ha, that is such a good point!