ASHP developments

[Beelbeebub]

3 minutes ago, JohnMo said:

Just the opposite with really you the end user live with short cycling all year and the energy cost hike.

Yeah but 99% of people don't notice or care.  As long as the house is warm and the hot water comes out of the tap they don't actually care what the boiler does. Most don't even know if it's running or not. 

 

To be fair, most won't care if their HP is short cycling as long as the house is warm and the water is hot. The issue is that *we* know it's bad and probably costing them money. 

Edited January 2 by Beelbeebub

[billt]

36 minutes ago, Iceverge said:

 

Interesting. 

 

How did you size your radiators and what flow temp do you use?

 

 

 I used a spreadsheet that I made to calculate the heat loss for each room (and used a few variations of insulation levels for comparison purposes). It's a spreadsheet that I made many years ago for our old house.

 

The Heat Punk website (https://heatpunk.co.uk/) gave pretty much the same answers when populated correctly.

 

I also used the Heat Geek guesstimator https://www.heatgeek.com/how-to-size-my-heat-pump-or-boiler-heat-loss-cheat-sheet/ for overall sizing, the Michael de Podesta rules of thumb

 

and some others that I can't recall.

 

Flow temperature was designed to be 35C.

 

[billt]

1 hour ago, SteamyTea said:

I am starting to think that the whole plumbing industry is not fit for purpose, and never was.  It has only survived because real heating engineers, working for manufacturers, can design easy to fit systems that bail out the knobs that fit the units.

 

I remember when my parents had a central heat system fitted (to replace the coal fired back bolier and Ascot water heater). I'm pretty sure that the plumber must have worked out the room heat losses and sized the radiators appropriately. In those days TRVs didn't exist, so you had to get the emitter sizes about right or the room temperatures would be wrong. It was so advanced that they had a room thermostat and a programmer!

 

When I fitted my first CH system about 1985 there were books available giving design methods for CH systems. I think most CH installers in those days would have made some attempt to design the system. The advent of combis with a grossly oversized boiler and TRVs removed the need for any design input to make a system that worked well enough.

[JohnMo]

Our last house circa 1820 build, we had a full replumb, plumber sized the radiators and said we need 4 or 5 huge radiators in our lounge. This forced me to do my own calculation. Ended up with 2 radiators, no issues. Very little engineering going on, monkey see, monkey do.

[Beelbeebub]

2 hours ago, billt said:

When I fitted my first CH system about 1985 there were books available giving design methods for CH systems. I think most CH installers in those days would have made some attempt to design the system. The advent of combis with a grossly oversized boiler and TRVs removed the need for any design input to make a system that worked well enough.

I think that's right.

 

People now have a slightly distorted view of how big a heat provider thry need. 

 

They look at their little 30kw combi in the corner of their kitchen then Google a 30kw HP and are put off by the cost and size of one, unaware they probably only need a 9kw unit.

 

IIRC the median peak heat demand for UK housing is around the 10-12kw mark, so a 10kw with 3kw booster heater would d do the majority of UK houses. 

Edited January 2 by Beelbeebub

[HughF]

9kW heat pump here, replacing a 12kW baxi Bermuda….

 

The house was always freezing before, rads woefully undersized even for dT50….

 

Designed for 45 degree flow now, run at 48.5 in the end, just to get things up to 23 to keep everyone happy.

[SteamyTea]

@HughF

You saying that a larger gas boiler did not heat your place, but the smaller, lower temperature ASHP does, and it was all down to the radiator sizes.

There are some on here who will never believe you.

[HughF]

7 minutes ago, SteamyTea said:

@HughF

You saying that a larger gas boiler did not heat your place, but the smaller, lower temperature ASHP does, and it was all down to the radiator sizes.

There are some on here who will never believe you.

More fool them, it was all down to rad sizing.

 

We increased the emitter size in all the rooms, by quite a margin, along with new primary pipework.

 

We had turned the flow temp down ‘a bit’ to try and make the rads less hot, but burn it for longer. The smart meter suggested we were using around 8kW when the boiler was firing. That corroborated my heat loss calcs.

[Roger440]

5 hours ago, Beelbeebub said:

A proposal I made for a different model of subsidy from the current lump sum for install. 

 

In short, the HP is installed with a "smart heat meter" basically the heat version of the smart gas and electric meters. 

 

It records the kwh heat delivered. It also records the electricity used (thus generating Cop as well).

 

The energy Co rebate the consumer for the difference in price between the cost of the heat delivered assuming a modern gas boiler (let's say 110% of gas price to allow for inefficiencies) and the cost of the ekectricity used to produce that with a HP assuming Cop of 2.5 (the carbon break even cop). 

 

This lasts for 5 years then tapers out over the next 5 so after 10 years there is no subsidy (or the assumed scop climbs over 10 years) 

 

So the consumer is guaranteed (assuming their installation is at least SCOP 2.5) not to pay more than gas. In fact if their system is better than 2.5 they "make" money.  That is the incentive to upgrade stuff like rads or insulation to boost the performance. 

 

The scheme is paid for via a levy on the gas price. 

 

There are some variation that can be played with like the starting scop, the taper rate etc. Also you coukd have it just make it so the cost is always the same as gas for the period, though that removes some of the incentive to upgrade. 

 

D

You also continue to offer subsidised upgrades like insulation or (say) a radiator scrappage scheme with money off new high performance rads when replacing old ones. 

 

Ahh yes, i remember now. So not something that exsists nor is even likely to exsist, any more than the guarantee im looking for as a consumer.

 

 

[Roger440]

7 hours ago, S2D2 said:

Yes, unless the heat loss calculation is not accurate.

 

Which yes, it might not be, even with an MCS registered installer.

 

So my point stands.

 

No guarantee, all on the owner.

 

Lets be realistic, on an old house of dubious or unknown construction, without very extensive work and some airflow testing, how can it ever be accurate. 

 

Id go as far as to suggest that majority of those heat loss calculations simply cannot be correct.

[Roger440]

6 hours ago, Marvin said:

"IF its designed correctly, then i will be warm."  Er... if the building has the designed thermal resistance and air tightness......

 

We are talking about retrofit, not new build.

 

So how do you do that, on lets say, my house. Half is an 1850's stone built cottage (with, currently wet walls due to cement pointing) And a 1970's cavity wall extension. With some but not all insulated plasterboard tent with hurricane behind. And a flat roofed bit on the side which i dont even know the construction of. That had a EPC bordering on D with an actual performance of about L.

 

I guarantee, even a really good assesor, isnt going to get this right in a short visit. Thats not realistic. But everything about the installation hinges on this assesment being correct. 

[Roger440]

6 hours ago, Bozza said:

A game changer for ASHP etc will be when the UK produces 100% or more of our electricity consumption consistently from renewables and no longer needs expensive fossil fuels to do so.  Some way off that though.  Scotland has hit nearly 100% already,  just need rest of GB to catch up.  

 

How wuill this make the installation better?

[Beelbeebub]

20 minutes ago, Roger440 said:

 

Ahh yes, i remember now. So not something that exsists nor is even likely to exsist, any more than the guarantee im looking for as a consumer.

 

 

It doesn't exist. 

 

There is no reason it can't exist. The tech is there. The numbers roughly work, and it would have the effect of guaranteeing the consumer doesn't pay more (for the 5 years) which woukd be a big block out of the way. 

[Roger440]

2 minutes ago, Beelbeebub said:

It doesn't exist. 

 

There is no reason it can't exist. The tech is there. The numbers roughly work, and it would have the effect of guaranteeing the consumer doesn't pay more (for the 5 years) which woukd be a big block out of the way. 

 

Doesnt matter how good you or i or anyone else thinks the idea is. We all know its not going to happen. So perhaps we should not go down thast rabbit hole and leave it to your other thread?

[Iceverge]

6 hours ago, billt said:

and some others that I can't recall.

 

Flow temperature was designed to be 35C.

 

 

A nice video that. Quite accessible. 

 

Did you consider oversizing even further and lowering the flow temp to benefit from a better COP? 

 

 

[Marvin]

3 hours ago, Beelbeebub said:

I think that's right.

 

People now have a slightly distorted view of how big a heat provider thry need. 

 

They look at their little 30kw combi in the corner of their kitchen then Google a 30kw HP and are put off by the cost and size of one, unaware they probably only need a 9kw unit.

 

IIRC the median peak heat demand for UK housing is around the 10-12kw mark, so a 10kw with 3kw booster heater would d do the majority of UK houses. 

Yes. Combi boilers are usually sized according to the hot water demand not the building heat demand.

[Marvin]

2 minutes ago, Iceverge said:

Did you consider oversizing the radiators even further and lowering the flow temp to benefit from a better COP? 

This is the whole point that lots of people don't understand. Low (low water temperature) and slow (slowly warming up the building) the way to go(most efficient and therefore least expensive way to heat the home)! 

[HughF]

1 hour ago, Roger440 said:

 

So my point stands.

 

No guarantee, all on the owner.

 

Lets be realistic, on an old house of dubious or unknown construction, without very extensive work and some airflow testing, how can it ever be accurate. 

 

Id go as far as to suggest that majority of those heat loss calculations simply cannot be correct.

How do people not know what their walls are made of and how much loft insulation they have?

[Roger440]

5 minutes ago, HughF said:

How do people not know what their walls are made of and how much loft insulation they have?

 

Why would they? I know way more than most people about my house. The majority of the population dont know anything about wall construction. Its just a wall.

 

And why should they know. They emply a professional in the belief that they will know. But how can they know the make up and efficency of a house in a 1 hour vist. Not realistic.

 

Ive been here over a year and i keep finding things, mostly leak paths, that i didnt know about. Even now, if got cold outside air circulating under the back bedroom floor. How would an assesor know that? It has a BIG impact on the heating in that room.

 

 

 

 

[JamesPa]

32 minutes ago, Roger440 said:

 

Why would they? I know way more than most people about my house. The majority of the population dont know anything about wall construction. Its just a wall.

 

And why should they know. They emply a professional in the belief that they will know. But how can they know the make up and efficency of a house in a 1 hour vist. Not realistic.

 

Ive been here over a year and i keep finding things, mostly leak paths, that i didnt know about. Even now, if got cold outside air circulating under the back bedroom floor. How would an assesor know that? It has a BIG impact on the heating in that room.

 

 

 

 

Why does hardly anyone think to use meter readings?  If current heating is gas, particularly if there is a smart meter, the heat loss is known pretty exactly if one just looks in the right place!

[Beelbeebub]

2 minutes ago, JamesPa said:

Why does hardly anyone think to use meter readings?  If current heating is gas, particularly if there is a smart meter, the heat loss is known pretty exactly if one just looks in the right place!

That's. Pretty much Podesta's method. 

 

I'm pretty sure modern boilers can record their output. The Worcester Bosch units have KW output. 

 

All they need is to record that along with the external temps. Should be able to calculate the heat losses from that. 

 

 

[JamesPa]

21 minutes ago, Beelbeebub said:

That's. Pretty much Podesta's method. 

 

I'm pretty sure modern boilers can record their output. The Worcester Bosch units have KW output. 

 

All they need is to record that along with the external temps. Should be able to calculate the heat losses from that. 

 

 

I haven't heard of Podesta (a reference/link would be appreciated) but ... Precisely!  External temps are actually known anyway from weather stations.  You could probably come close to inferring internal temperature from the data (because you know both the change in consumption and the change in external temperature from which you can pretty much infer the actual internal temperature, but better I grant actually to measure it for a while). 

 

I cant believe that Octopus aren't already working on this as they have tons of smart meter data, know where the meters are, and have an interest in heat pumps, particularly small ones.  Hopefully this will eventually put an end to the over-estimates that the spreadsheet jockeys tend to produce and with it at least some of the problems that heat pump deployments face because of poor design/installation.  A bit of AI should be able to replace the (frequently absent) human intelligence fairly easily I would have thought.

 

Edit - I found Podesta https://energy-surprises.blogspot.com/2022/06/how-big-should-your-heat-pump-be.html

Edited January 2 by JamesPa

[S2D2]

8 minutes ago, JamesPa said:

Podesta (a reference/link would be appreciated)

https://protonsforbreakfast.wordpress.com/2023/04/02/another-heat-pump-spreadsheet-beyond-the-rule-of-thumb/

[SteamyTea]

34 minutes ago, JamesPa said:

Why does hardly anyone think to use meter readings

Amazes me as well.

 

I posted up how to make a pretty accurate electrical energy meter and logger.  I have never seen a gas smart meter but suspect they have a flashing LED on them, so my design would work with them as well.  Some of the newer mechanical ones had a magnet on the spinning disk, so a change of sensor and it could read them.

The advantage of logged data is that you can see how long something is actually running for, which is most useful for sizing.

[JoeBano]

22 minutes ago, JamesPa said:

I haven't heard of Podesta (a reference/link would be appreciated) but ... Precisely!  External temps are actually known anyway from weather stations.  You could probably come close to inferring internal temperature from the data (because you know both the change in consumption and the change in external temperature from which you can pretty much infer the actual internal temperature, but better I grant actually to measure it for a while). 

 

I cant believe that Octopus aren't already working on this as they have tons of smart meter data, know where the meters are, and have an interest in heat pumps, particularly small ones.  Hopefully this will eventually put an end to the over-estimates that the spreadsheet jockeys tend to produce and with it at least some of the problems that heat pump deployments face because of poor design/installation.  A bit of AI should be able to replace the (frequently absent) human intelligence fairly easily I would have thought.

 

Edit - I found Podesta https://energy-surprises.blogspot.com/2022/06/how-big-should-your-heat-pump-be.html

I’ve done 2 winter trials with octopus. They tell me the day before when to turn my heat pump off and for how long for. I got £150 credit last winter.