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BEopt how to select multiple heat pumps?

asked 2021-05-04 06:56:01 -0500

escyr gravatar image

updated 2021-05-06 15:33:00 -0500

I've got my existing home design modeled in BEopt, but I can't determine how to chose multiple heat pumps as my heating source. Any ideas?

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answered 2021-05-05 11:52:18 -0500

If by multiple heat pumps, you are referring to more than one heating/cooling system for a single building/zone, then, as far as I know, you cannot do it in BEopt. If you want to use the analysis for sizing purposes, you can still take the total size and assume it is provided by multiple heat pumps with smaller sizes. Also, you can define a supplemental heating output capacity (more information here).

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To add to this answer, if there are multiple heat pumps with the same performance (efficiency), you can just treat them as a single aggregated heat pump in BEopt. If the heat pumps have different performance, you could create a weighted average performance based on the fraction of heating/cooling load (or floor area) that each would see.

shorowit gravatar image shorowit  ( 2021-05-05 12:21:22 -0500 )edit

Yes, I'm referring to more than one heating/cooling system for a singe building. There are both the same, identical MSHP units. I am trying to find my total heating load required for my home.

Are you saying if I enter in a supplemental heat source (electric baseboard), along with my MSHP, then when I run the output report, I just look at the supplemental heat source load to find my total heating load required for my home and ignore the MSHP heat load?

escyr gravatar image escyr  ( 2021-05-05 13:49:32 -0500 )edit

If they are identical and cover the same floor area, then all you need to do is to split it in half. If the floor area is different, follow what @shorowit mentioned. If there is no supplemental system in your building, then there is no need to do what you said. You will receive a warning message that you haven't modeled a backup electric resistance and you can consider it but you don't have to.

Ehsank gravatar image Ehsank  ( 2021-05-05 14:24:14 -0500 )edit

There is supplemental electric baseboards (with breakers turned off), but I'm trying to determine what the max heating load is for my home. Do I just use the Graph Type -> HVAC Capacities (kBtu/hr) = 19.1 as my required heating load for sizing heating equipment?

escyr gravatar image escyr  ( 2021-05-05 14:47:01 -0500 )edit

That number shows both heating and cooling for your heat pumps. You cannot get the heat pump's heating load separately. It is not useful either. You need the total capacity of your heat pump not just the heating load. If you want to size the electric baseboards, then you can select the option "Electrical Baseboard" and the Heating Capacity shows the baseboard's capacity. Whatever you do, make sure you also check the unmet hours (i.e., Loads Not Met) at the end. You might end up manually selecting the equipment size.

Ehsank gravatar image Ehsank  ( 2021-05-06 12:27:54 -0500 )edit

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Asked: 2021-05-04 06:56:01 -0500

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Last updated: May 05