Adding a Mini-Split?

[Jacob Racusin]

Hi there,

I have a project in which I would like to be adding a mini-split heat pump. There are two existing heating systems – a propane boiler for a radiant floor in an addition, and an oil boiler for baseboard heat in the main house. How do I add a mini-split, without removing or changing the existing systems?

Additionally, the propane boiler is in a garage. We are going to be building insulated walls/ceiling to keep the boiler in conditioned space, but I don’t see a provision for this – I can opt to describe the boiler as being in the unconditioned garage, but not to make an improvement, and I can change the distribution from “unconditioned” to “conditioned”. Any other knobs to turn? Thanks!

Jacob Racusin
New Frameworks Construction

[Gamaliel Lodge]

To add an third system, you just need to adjust the Pct Total controls on the improved side to remove load from the first two systems and activate the third system. You will have to use the detailed interface to do this.

We don’t have modelling to estimate the energy savings of bringing only the boiler inside the conditioned space. Changing the status of the distribution system would not be adequate, unless all of the distribution system was also located outside the envelope. The improvement that you are describing would improve the AFUE of the boiler by reducing some of the standby losses from the boiler tank. You will have to model this as an improvement to the boiler and estimate the change in AFUE yourself.

[Jacob Racusin]

Thanks so much for the reply, this makes sense. I’ll follow up with further questions, and proceed according to your recommendations.

Cheers,
Jacob

[Jacob Racusin]

I adjusted both the oil and propane “% Total-Fuel” values to be 15%, but I see no provision anywhere to activate or adjust a 3rd heating system. Please advise!

On another note, I just entered in three years’ worth of billing data for propane and oil in the Multiple Fuels chart, including the total period fuel amounts at the bottom of the pop-up, but when I attempt to conduct “Utility Analysis” I am told a fuel analysis is not available, and that the bills did not provide a good heating signal (same value for cooling, which has no data inputs). Thoughts? Thanks for your continued support.

Best,
Jacob

[Gamaliel Lodge]

You must use the detailed interface to access the third system. Go to the Heating page and click the “Switch to detailed” link at the top. There are buttons to access the second and third systems at the bottom of the detailed screen.

When you do a multiple fuel analysis, we can only work with the totals. This means there is no opportunity to dis-aggregate heating and base-load from the bills themselves. The totals are still useful for a whole building calibration. I should probably revise that message to make it more clear that the bills are still useful.

[Jacob Racusin]

Got it. Thanks!

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