Heat pumps

If 49.9% is the figure, fair enough, but it seems high to me.
Almost all of the electricity generated from gas in the UK is via CCGT, which is what you linked to earlier https://en.wikipedia.org/wiki/Combined_cycle_power_plant
where the gas is burned to drive a turbine directly and then the heat from that is used to create steam which drives a steam turbine. 50%+ efficiency is typical for those.

Open cycle gas plant is rarely used. It's only advantage is it's cheap to build, but it's very expensive to run as a very large amount of the energy is wasted. It's the same gas turbine part and then all of the heat is thrown away.
Occasionally used when there is a shortage of generation and the high operating costs don't matter because the price of the electricity that can be sold is also very high.

Burning anything else such as coal, wood, oil, waste and so on is far less efficient, 20-30% typically, which is also why electricity from coal is both far more expensive and has a much higher CO2 output per kWh, as vast amounts of the energy is wasted.

For any modern heat pump heating system, just forget about S plan, on/off thermostats and the rest. It's irrelevant.
While it's possible to shoehorn a heat pump into a place where a gas boiler was, just doing that will result in a low performing, expensive to operate system. That will be most or all of the systems that you will hear complaints about.
 
Sponsored Links
Almost all of the electricity generated from gas in the UK is via CCGT, which is what you linked to earlier https://en.wikipedia.org/wiki/Combined_cycle_power_plant
where the gas is burned to drive a turbine directly and then the heat from that is used to create steam which drives a steam turbine. 50%+ efficiency is typical for those.
I appreciate that now, I just hadn't realised CCGT was as prevalent. Open cycle is used on offshore platforms, where space is at a premium.
For any modern heat pump heating system, just forget about S plan, on/off thermostats and the rest. It's irrelevant.
While it's possible to shoehorn a heat pump into a place where a gas boiler was, just doing that will result in a low performing, expensive to operate system. That will be most or all of the systems that you will hear complaints about.
Yes, need plenty of rad area for a start.
 
And onto the efficiency figures achieved at the power station we can add transmission losses shipping the electrons through the cables to the point of use. There are losses in the gas grid of course but far smaller.
 
And onto the efficiency figures achieved at the power station we can add transmission losses shipping the electrons through the cables to the point of use. There are losses in the gas grid of course but far smaller.
Electrons move too slowly to be useful. Energy however does, instantaneously.

In any case it hardly matters as I know noone who has only a gas supply and not grid.

Besides, it's still more efficient and has numerous other benefits such as large scale balancing capabilities.
 
Sponsored Links
How much is involved in swapping an splan cylinder to a heat pump cylinder. New pump? Zone valves? I think the coil is bigger on the heat pump cylinder. Also there is a buffer tank that is linked too it?
 
How much is involved in swapping an splan cylinder to a heat pump cylinder. New pump? Zone valves? I think the coil is bigger on the heat pump cylinder. Also there is a buffer tank that is linked too it?
A decent system should have no buffer tank.
 
This is what I'm trying to learn can anyone recommend a manufacturer for training courses?
 
Mitsubishi do some serious design software, but ultimately a manufacturer is not where you should be looking for training - because the skills / knowledge are all true regardless of the heat source.

There is also very little penetration in the UK market - they will have a tough fight vs the encumbent 30 year old technologies who can offer "cashback at the trade counter" style business.
 
And onto the efficiency figures achieved at the power station we can add transmission losses
Yes, I mentioned this in earlier post. And in the DUKES stuff, the only reference I've found to efficiency talks about CCGT, coal fired and nuclear stations. I didn't think there were any coal fired stations left in UK. It doesn't mention the Drax station which burns wood chips (and only looks environmentally friendly due to some dubious accounting) and I would guess has lower efficiency than coal. Also I thought there were some stations using oil.
But if heat pumps do take off in a big way, will there be enough electric, green or not, to power them, along with the electric cars we're being urged to change to?
 
Last edited:
Yes, I mentioned this in earlier post. And in the DUKES stuff, the only reference I've found to efficiency talks about CCGT, coal fired and nuclear stations. I didn't think there were any coal fired stations left in UK. It doesn't mention the Drax station which burns wood chips (and only looks environmentally friendly due to some dubious accounting). Also I thought there were some stations using oil.
But if heat pumps do take off in a big way, will there be enough electric, green or not, to power them, along with the electric cars we're being urged to change to?
Without changing the cables that supply our homes? Would they need a larger supply, would a 80/100 amp breaker be enough?
 
Given the UK climate domestic heat pump installs should really be targeting a COP of 5. 3 would be a woeful design and/or install these days.
COP falls when the weather's colder. Is COP 5 achievable in the winter, when demand is greatest? Just asking, I don't know much about heat pumps, apart from the operating principle.
 
A 10kw heat pump would have a 40 amp breaker?
That would be for 10kW electric. Heat out 30 - 50kW depending on COP, which is a lot more than an average house needs. But it still needs to be designed in, and added to the other electrical loads.
 
This is what I'm trying to learn can anyone recommend a manufacturer for training courses?

Dare I suggest ringing Margaret on 01727 744002 and book yourself onto Riello's heat pump training course at either London Colney, Herts or Cleckheaton, West Yorks. I run it and I think it's intense but useful.

Free, no qualification at the end of a very full day and very little is about Riello product, the vast majority is about how, why when and what not to do, the implications of installing a HP.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top