Hybrid settings for Honeywell T6 Pro Smart for heat pump & Peerless.
Just had an install of a Bosch M20G 5 Ton AC/Heat pump and still kept my Peerless boiler/baseboard heating. I've been told for the heat on the Bosch to set it and forget it. But I'm trying to figure out when to have the oil burner kick in to assist the Bosch on very cold days in NY.
I turned the heat on only once when it was cold in the a.m. and if I recall, the baseboard AND the heat pump kicked in. I have the WiFi off. See no need for it.
The T6 came with the system and has a lot of ISU settings. Definitely a big learning curve. Could use advise. Thanks.
Comments
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That should have been set up with the installer.
There might only be a 1 or 2 degree differential before the boiler comes on. If you set the thermostat one degree above setpoint, only the Bosch should run.
The boiler should also run during defrost if there's a heat demand at the same time.
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Why run the boiler during defrost? It's not going to prevent cold air from blowing from the heat pump and I would think that the burner wouldn't run long enough to heat up the chimney enough to prevent condensing. I usually leave W from the outdoor unit disconnected on systems like this. I try to set up the system so the heat pump never goes into defrost if possible. Let the boiler take over if the temperature is below freezing.
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Ok. IDK how you prevent the defrost cycle unless it's not that cold. The newer systems have it built into the board on a timer and/or coil sensor. If you're lucky you can set the frequency.
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I usually set them up for switching over to the boiler or furnace at 35⁰, this minimizes the possibility the heat pump needing to defrost when the time and temperature defrost boards are set to 60 minutes.
With furnaces I worry about the coil being hit with high temperature air from the furnace during a defrost cycle. Maybe I am overthinking things, but I haven't had any complaints from customers with these setups.
Certainly with a Bosch inverter heat pump you can run it to much colder outdoor temperature without losing any efficiency compared to a single stage heat pump. I might set them up differently.
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What are your local utility rates? Also what is the model number of your outdoor unit? In my area anything oil is 3x heat pump cost so you never want to run it, gas is about even bellow 10F. About the only reason to switch over is if the heat pump runs out of steam or the air temp starts to drop on non EVI units.
Defrost cycles are simple to deal with. Simply turn off the circulation fan, most allow you to configure this. Works very well the only way you know that a defrost cycle is happening is that the house goes quiet for a minute or two. After the defrost most have a delay to allow the indoor coil to re-heat so it never blows cold.
The one you don't want is to use aux heat strip during defrost. This uses a lot of electricity for no reason.
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Outdoor model: BOVB-60HDN1-M20G
Indoor model: BVA-48WN1-M200 -
That unit is not a cold climate heat pump, so it does loose capacity as it gets colder:
https://ashp.neep.org/#!/product/66302/7/25000/95/7500/0///0
The COP on the unit is still decent though, so if you are replacing oil, it will save money to at least try to run at as long as you can. It will start blowing colder air though when it gets into deep freeze territory.
I took a quick look at the manual and it seems to be pretty basic compared to some of the hyper heat units I have used. Kindof looks like somebody slapped a Bosch sticker onto a domestic inverter heat pump. It doesn't seem to have a way of disabling the house fan during defrost which is not great. This is something that could be added with some external bits, not sure why it is not built in.
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If your T6 pro thermostat is a model TH6320WF2003 then you have what you need to set this up properly. You need to add the outdoor sensor and a RIB 2401D relay this will become your heat relay. It will be operated by the Thermostat AUX terminal. https://www.supplyhouse.com/Functional-Devices-RIB2401D-Enclosed-Pilot-Relay-10-Amp-DPDT-w-24-VAC-DC-120-VAC-Coil?_br_psugg_q=rib+relay
This is your wiring diagram.
With this Diagram you can set the compressor to lock out at any given temperature in the Installer Set Up (ISU) menu. Some key settings to look for:
- 130 = Wired
- 200 = Heat Pump
- 205 - Air to Air
- 221 = Heat stage =1 Aux/E = 1
- 255 = Fossil
- 256 = Fossil
- 260 = Thermostat
- 300 = Off
- 340 = 2. This is a starting point and may need to be changed based on comfort. Lower numbers may cause both the Heat Pump and the Peerless boiler to operate at the same time. If this is unacceptable another relay can be added.
- 355 = 34° this can be changed based on comfort
- 375 = 3
- 378 = 3
All the other ISU should be left at the existing settings
CAP unused wires on the RIB2401 relay individually.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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What I wanted to do is have the oil burner kick in during really cold temps when the Bosch unit is struggling. I currently have the Bosch unit running at 67° and the Emergency Temp for the boiler set at 65°. This morning the outside temp was 35° and it seemed that the unit didn't have a problem keeping the house at 67°.
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Since your backup is oil heat, I would keep the heat pump running as much as possible. Not sure how your thermostat is configured but you want the heat pump and boiler running parallel, even when it is not providing the full heat, it is still cheaper than oil so might as well use it to offset some of the heat.
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So have both oil and air run at the same time? I only have the oil heat for hot water at the moment.
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