Dual Fuel Heating Systems - Advantage or Compromise?

- Dual fuel heating systems combine a gas furnace with a heat pump. Is this a short term compromise or a good solution for home comfort?
Heat pumps are now the technology of choice for heating homes in the US. Sales of heat pumps are outpacing sales of gas furnaces for the first time as more homeowners become familiar with the advantages of this technology. Many installers however, recommend dual fuel systems which combine a heat pump for efficient cooling and heating with a gas furnace for back up heating during the coldest times of year. Other installers say these systems are unnecessary and a stand alone heat pump is a better solution.
Join us as we dive into this question with our panel of experts. We will discuss the pros and cons of dual fuel systems, when they might be a good solution, and the relative installation and operational cost differences between this solution and a stand alone heat pump. We will answer the following questions and more:
- What is a dual fuel system and how is it different than a stand alone heat pump?
- What are the practical issues that affect heat pump systems design?
- Are there situations where dual fuel is a preferred solution?
- At what temperatures should dual fuel systems switch to gas heating?
- Is dual fuel a better solution than a gas furnace with AC?
- What are the relative costs for dual fuel vs all electric systems?
- How do GHG emissions compare between dual fuel and all-electric systems?
- Do dual fuel systems have a long term role as we decarbonize buildings?
Panelists:
Zack Turner - Comfort Advisor, Climate Control. Zack has been in the HVAC industry for 13 years, and he takes a "home as a system" approach to help homeowners choose the equipment that best suits their needs. He loves the flexibility that the new generation of high-performance heat pumps gives homeowners to address common health and comfort issues. He is committed to offering electric options and sharing the advantages of electrification with all his clients.
Chris McKinney - Ductless VRF Manager, Airefco Inc. Chris has years of experience as an HVAC consultant, project manager, factory product manager and business owner. Chris is currently the Ductless and VRF Manager at Airefco Inc - the Pacific Northwest distributor for Carrier and Bryant products.
Theresa Pistochini - Ph.D. candidate and Engineering Manager at the UC Davis Energy Efficiency Institute and Western Cooling Efficiency Center. Theresa has 15 years’ experience in applied research in energy efficiency in buildings and Heating, Ventilation, and Air Conditioning (HVAC) systems. Through laboratory and field experimentation, and building energy modeling, she has researched methods to decarbonize buildings and reduce energy consumption, improve thermal comfort, and improve indoor air quality using indirect evaporative cooling, heat pumps, ventilation and filtration methods and controls. She earned her M.S. in mechanical engineering from UC Davis and is a licensed professional engineer in California.
Subhrajit Chakraborty - R&D Engineer, Western Cooling Efficiency Center, UC Davis. Subhrajit has 8 years of applied experience with thermal energy systems, electronics cooling, absorption refrigeration, and building heating, ventilation, and air conditioning (HVAC). His work focuses on building decarbonization through testing, modeling, and optimizing controls of various HVAC systems. Prior to UC Davis, Subhrajit was a technical lead at Carrier Corporation developing commercial chillers and heat pumps. He holds a master’s in mechanical engineering from Georgia Tech and is a licensed professional engineer in California.

[@geertaerts6566]

Thanks so much for this webinar! Brian & Theresa & Zack & Chris kinda addressed this - available cold-climate heat pumps have already outpaced the compromise gas backup or electric resistance backup solutions. The emissions modeling used old-fashioned heat pumps, so we're already outpacing those models. There's just too much potential for setting a 40-degree switchover temperature (I see this being used as the most common lockout in commercial applications), or leaving the thermostat on emergency electric backup, etc. to keep using gas backup or electric resistance backup.

[@BobQuigley]

Our gas supplier charges $45.20 per month regardless of gas usage. We're headed to all electric. Last project is air source heat pump and we will spend the $45.20 on more electricity if needed

[@geertaerts6566]

Yep, as soon as the climate-denying gas companies see their profits are going downhill, a gas connection is going to be so expensive to try to make up profits, that 99% of people will dump it within a few years.

[@jamierwheal]

curious about application for full off grid (no electric tie in) batteries only system at 10k'' in CO with serious snow events in winter and woodstove supplemental. R40 walls, R60 roof, triple pane windows, but our local contractors are steering us off heat pumps of any kind and straight to propane furnace only--any thoughts/advice?

[@ElectrifyNowUSA]

@jamierwheal wow I have never encountered an off grid heat pump system. I would think that would be a challenge due to the shear number of kWh you would need to supply with solar and batteries. I have no doubt a heat pump would provide the heating you need in a well insulated space, the question is getting it enough energy if you are not on the grid. Is it an option to tie into the grid for your heating needs? You would save a lot of money by not using propane - that is one of the more expensive fuel sources. Even a dual fuel propane/heat pump would be much less expensive to operate and give you AC in the summer if you need that.

[@gilbrook]

@Zack Turner, Why is a backup generator unable to run HP/air handler?

[@ElectrifyNowUSA]

It is possible, but you need a large backup generator.
www.pickhvac.com/heat-pump/basics/generator-size/