Optimising domestic space-heating retrofits from nat gas to heat pump

[DamonHD]

Hi,

So here is what I expect to spend (some of) the next ~8 years working on, officially starting 9th Jan (and ending, according to my offer letter, in 1931!):

https://www.earth.org.uk/PhD-research.html

Rgds

Damon

[bigrockcandymountain]

Very interesting.  I'll be following this closely. 

My mother has been asking about converting her oil furnace to a heat pump.  Her house is very poorly insulated, so i told her that would be a better place to start.  She isn't excited about tearing the place apart though.

I told her that air source heat pumps aren't viable here as a primary heat becsuse they don't work well below -15c.

I suggested a ground source heat pump.  I have the drilling rig to install this.  Maybe I'm wrong on this. 

Anyway, i know you'll do good work and that this research will be very valuable.  I'll learn what i can from it.

[Mary B]

They can spray foam by drilling a hole into each stud cavity on the outside of the house, same method for blown in insulation(this will settle some but it beats ripping all your interior walls apart).

[SparWeb]

Agree that insulation is better, and don't forget the attic space, if applicable to her house's construction.

Notwithstanding your offer to drill the GSHP loop (a kind offer!) I think it can also be installed horizontally, as long as it is deep enough below frost line.  I don't actually know how deep that would be here at 52 degree North latitude...

[DamonHD]

Very interesting.  I'll be following this closely. 

My mother has been asking about converting her oil furnace to a heat pump.  Her house is very poorly insulated, so i told her that would be a better place to start.  She isn't excited about tearing the place apart though.

I told her that air source heat pumps aren't viable here as a primary heat becsuse they don't work well below -15c.

I suggested a ground source heat pump.  I have the drilling rig to install this.  Maybe I'm wrong on this. 

Anyway, i know you'll do good work and that this research will be very valuable.  I'll learn what i can from it.

Thanks!

Damon

[bigrockcandymountain]

The frost line here is generally considered 6' below ground.  I think a horizontal loop installed at 8' would be workable.

I would rather do the vertical loops though.  The soil here, when disturbed, is really difficult to get packed back in the trench.  You end up with a sinking hole for the next 50 years. 

I think the basement would be the first place to insulate.  It is bare cinder block and full of cracks and drafts.  It is also poorly finished, and not used for much except storage.  A layer of poly vapour barrier, then a layer of rigid foam, then a stud wall with batt insulation would make a world of differnece. 

The upstairs is only 2x4 with fiberglass batts.  If it was mine, i would just add rigid rockwool panels to the exterior plus house wrap and put new siding on. I have suggested that but no enthusiasm so far.

And ya, the attic would benefit from blowing in some extra there too.  It is blown fiberglass and not super thick. 

Sorry about the thread hijack Damon. What are the biggest challenges converting hot water systems to heat pump? I would guess the lower operating temperature would have to be a factor.  I'm sure there are others.

[DamonHD]

Hey, no apologies needed, this is interesting real-world stuff!

One issue is the argument as to whether any heat-pump upgrade should wait until all insulation improvement is done.

Other issues are any need for radiator (up)sizing, and use of controls (eg how long in advance of getting up does your heat-pump need to come on rather than a gas boiler, use of TRVs or not), and new noise outside from external fans, etc.

There are lots of others, some of which I am resisting even typing here!  But a lot of the issues concern getting the humans fixed: those who specify and install, as well as those who are warmed (and/or cooled) by heat pumps.

About my first block on Mastodon was of someone who called me a traitor (to the US...) for living in a small (UK) house, not hating heat-pumps, and being familiar with PassiveHouse!  Or something like that.

Rgds

Damon

[MattM]

Maybe you can dig your vertical hole and drop a sealed pipe down at the top of your groundloop, with a thermalelectric coil in it for your dumpload.  The water would be pre-heated a bit closer to what you need for steam but would never reach steam levels.

[SparWeb]

The upstairs is only 2x4 with fiberglass batts.  If it was mine, i would just add rigid rockwool panels to the exterior plus house wrap and put new siding on. I have suggested that but no enthusiasm so far.

My father just finished a house and detatched garage.  Between finishing the house without exterior foam and the garage that does, he regrets not putting it on the house.  Both are heated, and aside from size, the garage needs much less energy to heat.  It was so easy to do before wrapping the garage during construction.
As a retrofit, adding external foam would damage/destroy the cladding if it's just cheap plastic.  The waste from that process would put a damper on my enthusiasm.

[SparWeb]

DHD,

Reading about your TRV (starting many years ago) has been my one and only contact with the nuances of these radiators. 

The differences between UK construction and NorAm. construction are pretty drastic, as evidenced in this conversation already.

Couple of years ago a French colleague and I drove past a house under construction (we were at an engineering seminar in Seattle). He didn't know what he was looking at because he had never seen wood-frame and sheathing before.  I almost typed OSB but you wouldn't get the reference.  This was an engineer with as much experience as me, so not a dummy. Such things are inconceivable in France (and likely the same in the UK).

Same goes for steam heating, I think.  I haven't seen it except once in my life, and that was a nearly-condemned apartment in old Montreal.  If I see radiators in movies set in the USA,  I automatically know it is set in New York. 

Someone correct me if I am wrong, if there are parts of the USA that use these a lot.

[MattM]

Our old church rectory in Nebraska had steam heating distributed through out three levels.  Because it added humidity, the heat was more comfortable than gas or electric furnaces.  I would imagine its still running today under the new owners.  We had groups using it up until it sold.  You could thaw out winter clothing in very little time, so was great place to meet after sledding events.

[Mary B]

Steam or hot water heat was popular up until the 70's where I live in MN. Many older houses have it, many had it torn out and forced air furnaces put in burning natural gas or propane. Many of those forced air furnaces have been upgraded, mine is now a 92% efficient unit vented with PVC pipe out a house wall.

[Bruce S]

Hi,

So here is what I expect to spend (some of) the next ~8 years working on, officially starting 9th Jan (and ending, according to my offer letter, in 1931!):

https://www.earth.org.uk/PhD-research.html

Rgds

Damon

Haven't looked at the entire thing but 1931!!

[DamonHD]

Yep, Y2K alive and welll!  (It's an 8-year part-time programme.)

Rgds

Damon

[Bruce S]

Damond;
I remember reading the logic behind your TRV system, and wishing it could be implemented here too! I also remember living in a couple houses with steam heat.
1) In Missouri when we moved up from the boot-heel when our father got a job with McDonnell Douglas working on the space program. It was wonderful warm heat with a cute little whistle from the valve at the top and a knob that would allow us to regulate the heat for that particular area.
2) When we moved up to SE Michigan that had a fuel-oil boiler that heated the water for the radiators. Again nice warm comfortable heat.

I also Applaud you for the amount of time you will be putting in for the PHD, 8 years worth!!

With due regard to the VERY Interesting topic at hand.
I believe that moving both to higher efficiency and adding insulation should go hand-in-hand. There is a point with insulation where the living space can be too tight and the air needs to be brought in from the outside (this can be done using exchange systems that will pre-heat or pre-cool the fresh incoming air) otherwise there will be issues with air quality.
Changing or upgrading heating/cooling systems to higher efficiency can be good for the home owner's pocket and the environment.

I look forward to seeing further information on this!!

Cheers
Bruce S

[DamonHD]

"Build tight, ventilate right" is how it should be.  We do indeed need to replace random uncontrolled drafts with controlled ventilation such as MHRV (heat recovery).

That 8 years is the equivalent of a mere 4 years full time.  %^>

The first paper I'm putting together on my site in public view (and may get slapped down for!) is here, trying to get my starting facts right:

https://www.earth.org.uk/UK-homes-needing-retrofit.html

The question of whether to retrofit a heat pump before insulating fully is a thorny topic, and one that I hope to understand!

Rgds

Damon

[Bruce S]

The question of whether to retrofit a heat pump before insulating fully is a thorny topic, and one that I hope to understand!

Damon

This is not just in the UK, it's pretty Thorny anywhere the subject pops up. 
The other item is whether there's a carbon increase during the retrofit.

There are air in filtration tests that can be done way before making a decision one way or the other.
I had one done when only to find the worse offender was my chimney.

Nice read BTW.

Cheers
Bruce S

[DamonHD]

When I had one (well two!) of those tests done, I discovered that my biggest uncontrolled ventilation was from a disused flue from a boiler that had been removed years before!

Rgds

Damon

[Bruce S]

There is one other concern, during the winter months,,, as it ever in the past 150 years gotten so cold that there wasn't any heat left to pull?

This is a real concern even for people in our area where the temps dropped to arctic temps ( was nice of Canada to send us a White Christmas !!  ) my family thoroughly enjoyed it , the little 11 yo Jack Russell NOT so much)
People who have the newer split heat-pumps had to go to using their backup heating systems Which included NG/LPG/Rocket Stove/???

Bruce S

[DamonHD]

There's only no heat available at absolute zero (0K), ie a bit below -273C, just to be picky!

Different heat pumps and refrigerants can work down to different external temperatures, and at worst a system can run plain old CoP 1 resistance heating.  Various reports I saw from the US across the last few days suggested mixed success even at very low temperatures.

In the UK the problem is less likely to be low temperatues per se, vs temperatures near 0C with significant humidity, causing the external system to ice up and need energy to de-ice.  Again, I have to see if the UK really is 'special' in this regard.

Rgds

Damon

[Bruce S]

You certainly have your work cut out!!
Let us know where & how we can assist!!
Even if it's just as sounding board. Sometimes you just need another set of eyes.

Cheers
Bruce S

[DamonHD]

Other sets of eyes will be very welcome.

At some point soon I'm going to have to get some journal papers written and formally peer reviewed.  Likely a lot less gentle and constructive than FL is.

Anyhow, I am assured that I mainly need persistence rather than genius, so I'm in with a chance... B^>

Rgds

Damon

[SparWeb]

Likely a lot less gentle and constructive than FL is.

...sound of sharpening knives in the background...  Yeah I'm up for a little critical review.

[Mary B]

There's only no heat available at absolute zero (0K), ie a bit below -273C, just to be picky!

Different heat pumps and refrigerants can work down to different external temperatures, and at worst a system can run plain old CoP 1 resistance heating.  Various reports I saw from the US across the last few days suggested mixed success even at very low temperatures.

In the UK the problem is less likely to be low temperatues per se, vs temperatures near 0C with significant humidity, causing the external system to ice up and need energy to de-ice.  Again, I have to see if the UK really is 'special' in this regard.

Rgds

Damon

Resistance heating IS NOT an option where I am!  Not with temps below -20f and gale force winds in winter. Heck the natural gas furnace barely keeps up in those temps. That is why I installed a pellet stove to help take up some of the slack! My house is as well insulated as it can get with 2x4 walls, blown in cellulose, inch of foil faced r board with all seams taped under the siding, newer windows... air leakage tests put it about equal with new construction! Couldn't be the 200+ cans of spray in foam I used over the years LOL 140+ year old house for part of it! Field stone foundation with 4" of sprayed on foam in the dungeon under the kitchen and 2" on all outside surfaces then covered with a textured R board that looks like cement. I have gone to extremes to block drafts!

[DamonHD]

Good that you have done all those things to minimise heat loss!

Rgds

Damon

[mab]

I would be very interested in your findings - except I'm having an ASHP installed right now and 8 years is a bit long a time for me to wait to optimise it. 

I'm building a house which is not to passivhaus standard but does exceed current UK build requirements for insulation and (i hope) air permeability. I've laid underfloor heating pipes with the ASHP in mind, but due to the fact that i have to use a registered installer (to claim the £5000 grant), i am dependent on the installers and manufacturers knowing what they are doing.

So far I'm not convinced that either of them do. 

But I'm doing my own research, and i suspect that once it's commissioned I'll be getting my own spanners out and making improvements - i just have to wait for the warranty period to elapse.

I recently did some fault diagnosis on a 13yrs old GSHP in the local village hall (17th century i think, solid stone walls, but new underfloor heating and floor insulation - 13yrs ago). The heating works well despite it being poorly insulated by todays standards, and the old heat pump that is on or off (as opposed to modern variable speed inverter driven compressors). So I'm expecting your eventual findings to be positive.

I think anout 2/3rds of houses in Norway use heatpumps ( not sure what proportion are air source though), where temps regularly are down to -20°c in winter i believe, and as you say, in absolute terms that's not that cold,  and it's the temperature range of the refrigerant that is the limiting factor.

Good luck with your PHD 

[DamonHD]

Hey thanks!

I promise that my intention is to publish anything useful ASAP as I stumble across it.  There's ~29M UK households behind you in the queue to upgrade to heat-pumps and I'd rather that as many as possible are done as well as possible.  B^>

Rgds

Damon

[DamonHD]

My first 'paper' (it's not going anywhere formal) is done...

https://www.earth.org.uk/UK-homes-needing-retrofit.html

TL;DR: ~20M UK homes already built and currently using nat-gas hydronic heating will still be with us in 2050 and almost all will need to be upgraded to heat pumps...  Luckily my simple calcs line up with those of the grown-ups the UK government appointed to give climate advice (the CCC)!

Rgds

Damon

[SparWeb]

If the study considers up to 25 million dwellings, of which 1/2 million are "technically unfeasible", then the problem with those exceptions is only the political side of their existence.  The climate effect of doing the majority of the dwellings but not addressing them is missing 2 % of your target.  Not technically enough to matter.  It's the existence of exceptions that will matter most.  The same might be said of the 2M "conservation" buildings but what I'm missing is what those really are.  If they aren't really dwellings but actually commercial/tourist/mixed use buildings then that's a whole different matter.  The consideration of dwellings only covers half of the uses that buildings get put to in the world.  If your county of Kingston is also considering retrofits to commercial buildings, they may find ways to deal with their "technically unfeasibles" there.

If a government-funded conversion program is too generous, then even the "technically unfeasible" building owners will subscribe, draining the fund on hard-to-fix buildings.  If the program is onerous to subscribe and comply to, then the exemptions granted to the "technically unfeasible" buildings will seed resentment among those who are forced to comply.  You can't win.  All you can do is seek the point of minimum pain.

Let's hope your work will help that point to be found.

[DamonHD]

Yesterday my first formal paper hit whatever the academic equivalent of the news stand is:

https://www.mdpi.com/2071-1050/16/11/4710

Domestic heating systems across northern Europe are responsible for a substantial fraction of their countries’ carbon footprints. In the UK, the vast majority of home space heating is via natural gas boilers with 'wet' hydronic radiator systems. Most of those use TRVs (thermostatic radiator valves) for micro-zoning, to avoid overheating, improve comfort and save energy. To meet Net Zero targets, 20 million such UK gas systems may be retrofitted with heat pumps. Heat pump system designers and installers are cautious about retaining TRVs in such systems in part because of worries that TRV temperature setbacks that lower heat demand may raise heat pump electricity demand in a "bad setback effect", thus wasting energy. This paper presents a new view of heat pump control and provides the first exploration of this issue through the development of a simple physics-based model. The model tests an installation industry claim about the negative effect of TRVs, and finds that though real it should not apply to typical UK retrofits with weather compensation. The energy efficiency benefits of TRVs for older and partly occupied homes, and to keep bedrooms cooler, remain valid. Comfort-seeking householders and installers should know that setting 'stiff' temperature regulation may invoke the bad setback effect and cost dearly in energy and carbon footprint.

Rgds

Damon

[Bruce S]

I see you're on Google Scholar!!

Cool 

Even though the vast amounts of the USA doesn't use hydronic heating, the read is still very interesting.

[DamonHD]

Thank you!

Damon