Hi all,

I'd be grateful to get your opinion on choosing a bid/equipment.

I'm adding central cooling to my Massachusetts house.

Proposals for equipment have included:

• 1.5 Ton single stage AC
• Bosch BOVA 2.0 with minimum cooling of ~14,000 BTU ___ What is the MAXIMUM Cooling?
• Bosch BOVA 1.0 with minimum cooling of ~11,000 BTU

Comprehensive Manual J not done
by a potential installer has cooling load of ~12,000 for the conditioned area.

Bosch minimum capacities were pulled from the NEEP Cold Climate ASHP site for the particular AHRI #s.
These Bosch heat pumps sound like a good product and value. Local installers are very confident in them.

Utility incentives make net cost much better for the Bosch 2.0 than 1.0,

but I wonder if the higher minimum cooling capacity would lead to less summer comfort.

__ BUYING A SECOND SYSTEM TO replace an improperly sized system
_____ is going to BE EXPENSIVE

Crazy to think I would let a rebate steer equipment selection,
but it is a significant amount of money.

Is the higher 3000 BTU of capacity,
or other differences between the BOVA 1.0 and 2.0, significant?

I'm not sure it would be worth spending $$$$ more on the 1.0.

Thank you

ZIP _ _ _ _ _
Floor Area _________ ?
Glass Area _________ ?

Residence Built _ _ _ _ / 2008 or 1958 ? /

Q. Sensible calculated _ _, _ _ _ BTU/HR
Q. Latent calculated _ _ , _ _ _

T H E N Equipment Selection

How does adding cooling Impact the duct layout ?
What is the impact on the furnace blower?

RESIDENTIAL HVAC DESIGN PROCESS

 

What Heat Pump or Hybrid systems were proposed ?
__ AHRI #s were not stated.


Design Temperatures: 7.7'F __ ASHRAE 99%

___________ 88.1'F / 71.3'F __ ASHRAE 1%

 

Duct improvements are also being made to ensure proper air flow for system and comfort. New, properly sized furnace will be installed together.

Equipment option 1:
AHRI Cert #:203377013
Outdoor Unit #:BOVA-36HDN1-M20G
Indoor Coil #:BMA*3036BNTD

Equipment option 2, more expensive:
AHRI Cert #: 206395978
Outdoor Unit #: BOVB-36HDN1-M18M
Indoor Coil #: BMA*2430BNTD

 

Duct improvements are also being made to ensure proper air flow for system and comfort.

New, properly sized furnace will be installed together.

Equipment option 1:
AHRI Cert #: 203377013
Outdoor Unit #:BOVA-36HDN1-M20G
Indoor Coil #:BMA*3036BNTD

Equipment option 2, more expensive:
AHRI Cert #: 206395978
Outdoor Unit #: BOVB-36HDN1-M18M
Indoor Coil #: BMA*2430BNTD

I suspect this thread will have > 90 Posts by May 3rd.

It appears that this contractor is proposing upto a 3 Ton unit for about 810 sq feet.

NO detailed response to Post # 2,
so NO design work can progress nor valid, realistic comments offered.

HEATING LOAD IS LIKELY TO GOVERN the equipment selection.

__ 392 CFM is not going to work on a 3-Ton HEAT Pump.

 

Design Temp
Summer OD: 87F
Summer ID: 75F
Cooling RH: 50%

Man J results (rounded)
Cooling BTU: 12,400
Sensible BTU: 9500
Latent BTU: 2900
SHR: 0.77
CFM: 392 Duct System can handle more at design ESP

Manual J was done with accurate window details and results of recent blower door test. Improvements to air sealing and insulation have been made throughout building envelope.

 

Screenshot with details on a proposed heat pump and evap coil combo. I'm not sure where NEEP gathers this information on cold climate heat pumps. Is the data reputable?

I came to consider this equipment for these reasons:

2. This heat pump starts quieter than simple AC compressors (in my experience)
3. I don't want to pay big $ for a 1 Ton modulating AC that is not commonly installed in my area. Rebates make heat pumps like this comparable in cost to simple ACs.
4. The ability to heat with electricity for shoulder seasons and limit short-cycling of the furnace is a bonus.

To my original question: is the minimum cooling load of this heat pump at 14,000 BTU, so much higher than my design cooling load of 12,000 BTU that I should be looking for different equipment or istallers?

Thank you

 

https://budgetheating.com/v/vspfiles/downloadables/BOVA36-60HDN1-M20G Technical Specifications.pdf

PER CODE, ONE MUST USE
________ Manufacturers EXTENDED Performance Data

 

I looked into this extended performance data and found this below. Have I highlighted conditions that might expected in my situation? Would this performance match up with my expected SHR of 0.77?

 

Yes, a 14,000 unit is absolutely fine for a 12,000 BTU load. Air conditioners are only available 6000 BTU increments at best, you are never going to get an exactly precise match and most installed have a much bigger discrepancy with the load than that while still giving adequate comfort. Manual S calculations give a precise answer to what equipment works with a given Manual J result.

That performance data is for a 36K air handler, not sure whether Bosch publishes the expanded data for their furnace coils. But assuming similar, and ideal comfort conditions of 75 F, 50% RH, yes the SHR matches up.