Comments on: Converting Heat Pump Capacity Between English and Metric

By: RoyC

RoyC — Thu, 02 Jun 2022 16:59:22 +0000

In reply to Allison Bailes. So shouldn't our electric bill be in Joules instead of kilowatt-hours?

By: RoyC

RoyC — Thu, 02 Jun 2022 16:55:59 +0000

David, most heat pump manufacturers offer heat pumps and controls that will allow it to work with a gas furnace without the need for strip heat. The controls either run the heat pump until it can’t meet the load, then it switches to gas heat or it switches to gas heat at a pre-defined outdoor temperature. Some call this a dual-fuel (not duel-fuel) system and one OEM trademarked it as “hybrid heat”. If your contractor is not aware of this, find another one who is.

My first house was dual-fuel. The installer connected it up so that the furnace could run simultaneously with the heat pump when needed. He didn’t believe me when I told him you can’t do that, but he changed his mind two weeks later when he replaced the compressor.

By: Allison Bailes

Allison Bailes — Tue, 31 May 2022 11:11:04 +0000

In reply to Bob Seaton. Yes, that's correct, Bob. The watt is a confusing unit for a rate because it hides the time part. As you point out, a watt is Joule per second.

By: Bob Seaton

Bob Seaton — Fri, 27 May 2022 16:14:10 +0000

Hi Allison,

Is it correct to think of BTU/hr and kW as rates? Rates of heat transfer?

So one kW (1,000 joules per second) is the same rate of heat transfer as 3,412 BTU/hr?

By: John M6

John M6 — Wed, 25 May 2022 13:21:52 +0000

As a computer type I frequently wish that home sap did have 16 fingers so our arithmetic would all be in hexidecimal.

By: David Power

David Power — Tue, 24 May 2022 15:12:23 +0000

I’ve been shopping for heatpumps so this is a timely article. After have several contractors give me estimates it’s obvious what one problem is, I currently have a gas furnace and the additional charge to upsize the electrical service for emergency strip heat makes it quite expensive. I inquired about a heat pump with a gas furnace as my backup heat and just get blank looks. As one of my mini-splits works well below zero F this would seem to be a cost effective solution but doesn’t seem to be available in the current contractor sales handbook. But having to spend thousands of dollars to upgrade the electrical service that almost never gets used. There has to be an intermediate solution.