Technology Connections does heat pumps (USA)

[George]

Thought some of you may find this interesting.

 

As in the UK, there are issues in the USA with oversizing gas heating and that makes it appear that heat pumps can't cope.

 

He went to the level of waiting for a polar vortex and using electric heaters to measure the true heat demand of his house. Although I warn you, the test is some way into the video and it's a long one.

 

 

Edited March 7 by George

[SteamyTea]

He sums it up well.

Where is the shorter version?

 

Here

 

 

Edited March 8 by SteamyTea

[sharpener]

Thanks, convincing and well presented.

 

V interesting that the USA is in more or less in the same (poor) position as the UK  even though their existing technology is quite different. I am supposing this is a warm/cold air ducted system as there is no mention of emitter type, condensing operation or WC.

 

With a hydronic system measuring the "call for heat time" would be an over-estimate bc call for heat does not equate to firing, a boiler would shut off on its own thermostat and cycle/modulate to keep its setpoint. However measuring gas consumption as per Michael Podesta's method equally valid.

 

-24C OAT! We hardly know we are born in the Gulf-Stream-washed UK do we? My design temp is -0.2, admittedly that uses stats for Plymouth. Have seen - 4.9C one single day in the last ten years. Plenty of secondary heat sources, although not permitted in MCS calcs.

 

Tools called "measuring tapes"!!!

 

Wonderful how they still intermix metric and imperial units, 2 tons HP equals 7kW, who knew?

[SteamyTea]

1 hour ago, sharpener said:

2 tons HP equals 7kW, who knew

https://en.wikipedia.org/wiki/Ton_of_refrigeration

 

And a BTU is

https://en.wikipedia.org/wiki/British_thermal_unit

 

[RichardL]

I don't know - seems part of the problem is a mistrust, or can't be bothered/afford to learn, or can't measure accurately heating requirements using the extrapolate from materials/rooms sizes etc method.

For whatever reason that approach (fabric measuring) wasn't used on pre-heat pump sizing - the trades/installers - just scaled up to make sure there was enough.

Just because heat pumps amplify the rule-of-thumb & experience methodology is not good enough - that on its own won't drive change before the heat pumps get a bad name for themselves (already happened)


A rule of thumb method - even the controlled test Tech.Connections did may work better to ramp up use of heat pumps?

I don't think I'm a luddite re methodology - just looking at what happens on the ground.

Post-note - you could regulation the heck out of it and try and make that regulation mandatory (see MCS) -  
That doesn't tend to solve the problem though -  I suspect it needs a simpler rule of thumb/sizing methodology.

Edited March 12 by RichardL

[sharpener]

 

1 hour ago, RichardL said:

For whatever reason that approach (fabric measuring) wasn't used on pre-heat pump sizing - the trades/installers - just scaled up to make sure there was enough.

 

Marginal cost of a bigger boiler is small. Often dictated (or so ppl thought) by HW requirement. Neither true for HPs.

 

1 hour ago, RichardL said:

I suspect it needs a simpler rule of thumb/sizing methodology

 

Well Michael Podesta's method of dividing annual gas consumption in kWh by 2900 couldn't be very much simpler. Heat Geek cheat sheet method of estimating from sq m and type of building construction is a good way of sanity checking.

 

Problem with retrofit is determining what the actual construction details are e.g. how much insulation is under the slab, and actual air changes/hour. Test methods exist but cost £many 100s, and some can't be done at some times of year so ppl aren't in the habit of using them.

[RichardL]

4 minutes ago, sharpener said:

Well Michael Podesta's method of dividing annual gas consumption in kWh by 2900 couldn't be very much simpler. Heat Geek cheat sheet method of estimating from sq m and type of building construction is a good way of sanity checking.

That works -  much better than measure everything guess materials - for existing builds.
IMO you'd have a much better chance of a. making that work with installers, b. be understandable by the customer -  than the current standard approach.

I don't doubt the latter (measure heat loss & calc sizes etc) works - it needs work on making it transparent and be seen to be working.

[SteamyTea]

1 hour ago, sharpener said:

Well Michael Podesta's method of dividing annual gas consumption in kWh by 2900 couldn't be very much simpler

As I am already all electric, could change that 3000 as the efficiency is better.

So that works out at 1 kW, which is probably about right.