Optimal Settings for Heat Pump with Hydrocoil as Aux

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p12nash

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I have recently had a Bosch IDS Premium Connected Heat Pump Model #BOVD-36HDN1-M20G and Air Handler Model #BVA-36WN1-M20 heat pump system installed with a hydrocoil connected to my Navien NFC-250/175H firetube combi boiler. The system is split into 2 zones, 1 for the 1st floor and 1 for the 2nd floor. I retained the previous radiators and have them connected to 1 thermostat that drives both floors. This thermostat is set low and doesn't run the radiators, however it would if there was a failure of the other heating system and the indoor temp dropped too low. I have a few questions about getting the settings for my system dialed in.

  1. The installer for the Navien said they usually don't mess with turndown settings. I feel like this is losing efficiency - am I right, and should I be adjusting that? I am located a little North of Boston, MA on the coast. My home was built in 1930, but has been recently reinsulated with blown in in the walls and attic.
  2. What are the optimal baseline settings for my aux heat? I have Ecobee 3 lite thermostats that are set to the following:
    1. Configure Staging- auto
    2. Aux Savings Optimization- 2.9F
    3. Aux Heat Max Outdoor temp- 50F
    4. Compressor Min Cycle Off Time- 300 sec
    5. Compressor Min Outdoor Temp- 35F
    6. AC Overcool Max- Disabled
    7. Aux Min on Time- 5 min
I appreciate any advice you are able to provide.
 

Fitter30

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What boiler temp are you running? Any condensing boiler is 95%+ efficient when return water is 140° or cooler. The cooler the better. They get their efficiency from the condensate. Above 140° drops/to 87%.
Pulled the spec on the outdoor unit sheet -4° lowest temp that bosch specs. All hp lose capacity the colder it gets. 24k unit 18k heat -4° at 47° 27-28k. The hot water coil will run with the radiators if not how are they controlled? The hp and the hot water coil are in the supply air and how are they controlled? How are they split with one air handler? Take a few pics of the indoor equipment and piping.
Need to know electric and gas per kw and therm all in taxes, demand charge/ delivery. Need this to compare btu to btu cost. With how electric companies charge its on a sliding scale and demand charge changes for a little and goes up with usage. Same with nat gas.
Setting -wouldn't change turn down settings i have no idea if what their looking at is the same for both hw and heating I've never seen that setting. Aux heat 50°. Hp goes down your going to need heat up to the mid 60. Normally dead band on thermostat is 2° heat drops 2° before calling. Boiler side outdoor reset might help. Anytime there are changes take baby steps. Change one thing at a time not more than 2-3 ° .and what how it operates write down in detail all changes.
 
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p12nash

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Boiler temp for the space heating is set to 136F

I have a total of 3 ecobee lite thermostats. There is one in the upstairs hall that controls the 2nd floor forced air system (heat pump and hydrocoil), one in the downstairs living room that controls the forced air system, and one in the downstairs living room that controls the radiators for both the first and second floors.

The indoor air handler unit is in the attic with the hydrocoil attached just after it. This is then split into two main trunks that span the attic with a zone damper. I have 5 registers in the ceiling in the 2nd floor with a large return in the hallway ceiling and 3 registers in the ceiling in the 1st floor with a return located on the wall near the floor. The supply trunks are zone, but the returns are not. This system was previously just air conditioning on one zone and my heating was provided by hydronic radiators. When the heat pump was installed they added the hydrocoil, first floor return, and zoned the system by splitting off the 1st floor ducting and connecting them to the new 2nd trunk.

My boiler has 2 zone pumps. 1 that is connected to the hydrocoil on the air handler in the attic and 1 that is connected to the cast iron radiators throughout floors 1 and 2. The indoor air handler unit has a control box that connects it, the zone damper, the boiler zone for the hydrocoil, and the 2 ecobees.
 

Fitter30

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Boiler temp for the space heating is set to 136F

I have a total of 3 ecobee lite thermostats. There is one in the upstairs hall that controls the 2nd floor forced air system (heat pump and hydrocoil), one in the downstairs living room that controls the forced air system, and one in the downstairs living room that controls the radiators for both the first and second floors.

The indoor air handler unit is in the attic with the hydrocoil attached just after it. This is then split into two main trunks that span the attic with a zone damper. I have 5 registers in the ceiling in the 2nd floor with a large return in the hallway ceiling and 3 registers in the ceiling in the 1st floor with a return located on the wall near the floor. The supply trunks are zone, but the returns are not. This system was previously just air conditioning on one zone and my heating was provided by hydronic radiators. When the heat pump was installed they added the hydrocoil, first floor return, and zoned the system by splitting off the 1st floor ducting and connecting them to the new 2nd trunk.

My boiler has 2 zone pumps. 1 that is connected to the hydrocoil on the air handler in the attic and 1 that is connected to the cast iron radiators throughout floors 1 and 2. The indoor air handler unit has a control box that connects it, the zone damper, the boiler zone for the hydrocoil, and the 2 ecobees.
Fan coils, radiators and fin tube all start to heat with 140° water and max out 190° where most boilers max out without tripping out on high limit. Your heater has outdoor reset only needs outdoor sensor mounted on the north side of the house. They make high performance coils, fin tube radiators that are design for lower water temps below 140°.
 
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