Missed Opportunity Heat Pump Water Heaters

[jar546]

The ICC missed a big opportunity to have some language in place to address the issues we are encountering with Heat Pump Water Heaters (HPWH) and took no action. As usual, the Homebuilders Association was against it, which leaves many gaps with installation inside homes, especially those that require heating. Much of the cold air is discharged inside, taxing the heating system and potentially creating false temperature readings on thermostats.

The manufacturer installation instructions are the only things to go by and don't take into consideration many of the unique situations. This is a problem for designers and builders and puts a lot of pressure on the plans examiners and inspectors.

 

[Inspector Gadget]

I discussed these gizmos with the area's best plumbing outfit, and they simply do not recommend them for multiple reasons. At the very least, these are only suitable for areas that are naturally quite hot, ie: industrial zones where heat is part of a manufacturing process. Otherwise, I don't see the merit.

 

[jar546]

I discussed these gizmos with the area's best plumbing outfit, and they simply do not recommend them for multiple reasons. At the very least, these are only suitable for areas that are naturally quite hot, ie: industrial zones where heat is part of a manufacturing process. Otherwise, I don't see the merit.

Unfortunately they are flying off the shelves right now as plumbers are installing them all over the country and in some instances they are spec'd out but the government.

 

[steveray]

Keeps my sisters garage cool in Florida....

 

[tmurray]

I discussed these gizmos with the area's best plumbing outfit, and they simply do not recommend them for multiple reasons. At the very least, these are only suitable for areas that are naturally quite hot, ie: industrial zones where heat is part of a manufacturing process. Otherwise, I don't see the merit.

When it comes to trades persons, they have valid opinions on installation and servicing issues. Unless they have training in energy efficiency modelling, their opinions would not be more valuable than any other person. I find a lot of tradespersons try to find reasons why they should not use new equipment or construction methods rather than have an open, data based mindset.

Cold climate heat pumps heat an entire house well down to -25C (some are getting into the low -30C now). It isn't really logical to think that we can heat an entire house, but can't heat or pre-heat some water.

I find a lot of people get hung up on the Fahrenheit/Celsius temperature range, but refrigerant is a completely different fluid so what feels cold to us or when water freezes is largely irrelevant.

 

[Inspector Gadget]

When it comes to trades persons, they have valid opinions on installation and servicing issues.

This was the primary cause of concern with the plumbers in question: the chap I spoke to (who I consider to be top shelf and work for a very good company) said they've had to replace every one they've installed within a year due to failures.

 

[wwhitney]

At the very least, these are only suitable for areas that are naturally quite hot, ie: industrial zones where heat is part of a manufacturing process. Otherwise, I don't see the merit.

The worst-case efficiency of a heat pump water heater is to act like a resistance electric water heater. Let's assume the water heater is located inside the thermal envelope. So sure, if you are in a heating-only climate, and if your space heat is electric resistance, there's no point in using a heat pump water heater, a resistance electric water heater will perform the same without the extra complexity.

But for every other situation, the heat pump water heater can perform more efficiently than electric resistance. Certainly if you are in a mixed heating/cooling climate, during the cooling season the heat pump water heater inside the thermal envelope will reduce your space cooling demand. During the heating season, it will piggyback on your space heat source. So if that source is anything other than electric resistance heating, your water heater will behave like it is mostly using the same heat source (with a fraction of electric resistance behavior mixed in, since the electricity consumed by the heat pump will end up as heat in the air or in the water).

Cheers, Wayne

 

[tmurray]

This was the primary cause of concern with the plumbers in question: the chap I spoke to (who I consider to be top shelf and work for a very good company) said they've had to replace every one they've installed within a year due to failures.

That sounds a lot like installer error. Lack of maintenance shouldn't cause them to fail after a single year.

I know a few people who have had them in their houses for years with no issues.

 

[jar546]

Keeps my sisters garage cool in Florida....

It is excellent for that if you live in our climate.

 

[Paul Sweet]

I expect that a lot of them are installed in rooms that are too small, so they keep driving the temperature down and have to work even harder until something gives out. They're probably OK in an unfinished basement, but a utility room or closet would need a louvered door and a nearby room to duct the chilled air to.