Heat Greek vs Skill Builder mainly heat pump, but some reference to condensing gas boilers.

[ericmark]

I watched in all about 5 videos, the first basic slated the heat pump, but by the end, it was shown it was saving money, must have been around 3 hours of video, but one thing the heat geek did say in passing, was the gas boiler can be set up better as well.

So he was in the main talking about the circulating water temperature, the lower it is, the more latent heat a gas boiler can extract, and the efficiency of the heat pump also increases, and in both cases on/off control is bad. And he explained why weather compensation was so important.

Since the guy had fitted massive triple radiators in his previous attempts, the circulating water temperature could be very low, but the idea of leaving all internal doors open, and heating all rooms 24/7 seems a little daft to me. However, the analogue control seems good. Yet, I would think 90% of homes have on/off controls.

My late parents fitted a new system, none of the old pipes or radiators used. It was a modulating boiler, which I in the end, got to work well, but as installed no TRV in the hall, the thermostat

used a mark/space ratio to stop over shooting, and the power shower was connected to a combi-boiler, all the lock shield valves were left wide open, it was in a nutshell a very poor installation, where the installer was aiming at the vulnerable to grab government grants. Using in the main semi-skilled labour, who would simply do as they were told, even if wrong.

However, when I corrected the errors, I realised the big problem was the Worcester Bosch boiler had no option to install an electrical analogue control, the only way to control it was the return water temperature, and it took a Winter living in the house to adjust the lock shield valves, so each room sat at the selected temperature all day, and the wall thermostats only job was to turn off heating when we had warm weather.

So I can see the point in having installers who are heat geek trained, as clearly many are not installing and commissioning the installation correctly. And both the heat geek and the Skill Builder guy seemed to agree, the problem is we have a whole new system, but a complete lack of re-training in how to instal these new systems.

I am only an electrician, I have the lowest of low degree, so I would ask those who have trained as heating engineers, what sort of degree is required to ply their trade, and are they too many non engineers (those with only level 3 qualifications) passing themselves off as engineers, who work on the idea, this is the way we have always piped and controlled central heating I see no reason to change.

The last video recaps all which had happened, they said 50% of plumbers are over 50 and not interested in retraining, I wonder how true.

 

[Wayners]

I've never seen a heat pump. I know someone that has one in a new build and is happy with it. I can't see how they are cost effective. Can you get someone to fix short notice? How reliable? Saving worth the cost of installing?

 

[cdbe]

My brother in law is retiring and moving to the Scottish Highlands - they're buying a rural doer-upper. He's raving on about heat pumps and acknowledges the need to upgrade insulation - he's thinking a bit of celotex stuck on the internal walls - I was thinking "passivhaus" standards.

But then I think that by the time you've made your house capable of being heated by 3 candles with plant pots over them, why would you spend all that money on heat pumps. Given they're mainly off the gas grid surely half a dozen propane cylinders and a heat only boiler with a solar/solar electric hot water and some battery storage would be cheaper? It seems it has to be what's fashionable rather than what's the best mix of old and new technology.

 

[Mister Banks]

Heat pumps aren’t about saving money so don’t think about ROI, after all who thinks about ROI when buying a car! If you want to do something positive for the environment, however tiny that this, then heat pumps are the best way of heating a property. What we need is for the ridiculous price of electricity to come down and then we will be saving money with a heat pump.

Gas and oil boilers are being phased out so everyone needs to think to the future and reconcile themselves to the reality of heat pumps.

 

[Why Not Indeed]

Given they're mainly off the gas grid surely half a dozen propane cylinders and a heat only boiler with a solar/solar electric hot water and some battery storage would be cheaper?

How long can you wait to see a return on investment? The relative costs of gas and electricity and relative efficiencies of the two systems determine which is more cost-effective. If mains gas is roughly 1/3rd the price of mains electricity per kWh you need a COP of at least 3 for a heat pump to be cheaper to run than a mains gas-fired boiler. I don't know how bottled gas and mains gas compare in price [at least there is no standing charge for bottled gas but presumably you would have additional costs for maintaining your little bit of gas infrastructure].
Bear in mind that solar electric hot water can only ever achieve a COP of 1, and solar thermal hot water is going to be insufficient for much of the year.
TBH your proposed system design could actually be the worst of all worlds

 

[Why Not Indeed]

What we need is for the ridiculous price of electricity to come down and then we will be saving money with a heat pump

Doesn't have far to go. Average electricity price I paid in most recent billing period was 18.8p/kWh and gas is 6.16p/kWh so a COP of 3 would do the trick for me.

 

[trojanhawrs]

My understanding is that heat pumps can be cheaper than or similar to gas to run but most older properties will need a completely new system to make best use of it. Underfloor heating is the best match for it but hot waters where you're going to lose the most efficiency in the winter months. Insulation does not have to be particularly good providing the pump/emitters are sized correctly

 

[ericmark]

Can you get someone to fix short notice?

This was their main point, there are not enough people able to fix them.

Bear in mind that solar electric hot water can only ever achieve a COP of 1

It seems that's not the case, but when heating the domestic hot water the heat pump is not doing central heating as the temperatures required are so different.

However the guy in question has retained his gas boiler, and this is the big question, is how does one heat the home with a power cut? If the heat pump fails one can use a simple fan heater or oil filled radiator, but if the electric fails, one needs a back-up, I have a battery which will keep my boiler running for a time, and if that fails, will take minutes to remove the cover from the open fire.

Solar may keep my central heating running, it would depend on state of charge of the batteries when we got a power cut, but no way will solar keep a heat pump running.

When we stop getting news reports like

About 57,000 homes and businesses are still without power across Wales after Storm Darragh battered large parts of the country.

Then we can look at heat pumps, and not before.

 

[Harry Bloomfield]

So he was in the main talking about the circulating water temperature, the lower it is, the more latent heat a gas boiler can extract, and the efficiency of the heat pump also increases, and in both cases on/off control is bad. And he explained why weather compensation was so important.

Since the guy had fitted massive triple radiators in his previous attempts, the circulating water temperature could be very low, but the idea of leaving all internal doors open, and heating all rooms 24/7 seems a little daft to me. However, the analogue control seems good. Yet, I would think 90% of homes have on/off controls.

Then I must be in that 10%, who also see it as being important/worthwhile. The difference is very, very noticeable, when compared to basic on/off control, and I have experienced both types of control, on the same boiler. On/off, it simply ran noisily, and flat out, until it hit temperature, with maybe a little modulation towards the end of the burn. That was followed by similar noisy 'burn' sessions, amid much creaking of pipes, as the heated and cooled. The variation in room temperature, was also quite noticeable.

I then swapped those basic controls out, for a full set of of room temperature and weather temperature compensated controls. It still starts the burn noisily, for a few seconds, but it rapidly settles to near silence as it modulates down. Gone was the creaking of pipes, and the noticeable variation in room temperature. My radiators just maintain a steady, constant heat, a consistent temperature. The only way to know how cold it is outdoors, without going out to check - is by feeling the temperature of the rads..

I'm getting a definite impression that the new control system is saving gas, though almost impossible to actually calculate in a domestic environment, except under lab conditions.

I have come across such systems before, mostly installed of large commercial, multi-boiler installations, involving a large, custom-built panel, custom software, to do the optimisation.

My radiators, are the very same ones installed in the 1980's, sized for drafty doors, and windows, plus single glazing, and no CWI. Since when, I have dealt with all those things, which means my radiators are now well oversized. Oversized, means the radiators can be run cooler, and the return water to the boiler, likewise cooler - so more chance for it to run in condensing.

 

[ericmark]

I got mother's house to modulate, here the boiler is simple on/off so no option, and yes radiators just warm, except when temperature change, but it seems the latest versions of heat pump can modulate, but in the main simple on/off. Which means size is important. Too big as bad as too small.

This house three stories, 5 bedrooms, 2 kitchens, three bathrooms are heated with a 19 kW oil boiler, and it has no problem heating the house. My mother's house had a 28 kW boiler, why? Only had 3 bedrooms.

So we see a home with an oversized gas boiler, not set up correctly, and the heat pump that replaces it is set up spot on, and just big enough for the job, so not comparing like for like.

Heat pumps can clearly work, I had an air-to-air cassette heat pump in Hong Kong, and before that Algeria, the latter in the 1980s. But it was used mainly for cooling. However, they have been around for a long time. But in Hong Kong with cassette heat pumps you switched it on in the room being used, which is how I use my central heating, I set times for each room, and if I am not going to use the room, I don't heat it. I have doors on rising butt hinges, so doors naturally close, actually have a stuffed gnome at door jamb to keep slightly open for cats.

Christmas with visitors we may heat all rooms, but that is unusual, not the norm. First house we had vents in all internal doors, and ducted hot air central heating, worked well, but cost a fortune to run as could not turn off rooms not being used.

 

[martygturner]

Never quite sure why a physics question on efficiency becomes a belief mission statement based on well I did this or that and it works for me.. The biggest issue in heating any home is its thermal system efficiency..not the efficiency of the source of its heating.

Eg you might have a heat pump with a cop of 3 but if its trying to heat a house with a system efficiency of say -4 then it will never do it efficiently.

It the same with all the old wives tails that come up - ooh don't heat a room as that will be more efficient...you cannot get round thermodynamics...heat flows from hot to cold, all you are doing is heating that room wastefully, it will be heated because you cannot get round the fact that its in your house and its colder than the rest of the space, heat will travel to it, you have left a freezer door open.

If you do want to heat your home as efficiently as possible...get the humidity down, recover all that lovely free latent heat that you are making by just being alive rather than transmitting it to heat up the universe and you will be able to heat the space to a lower level and feel more comfertable.

There are some tables out there, but at 40% humidity we humans need a stable air temp of 17.6 c to feel comfortable and at 65% we need 19.7c.

All these skill builder / heat geeks never attack the issue of what you are heating only the source of its heating...