ASHP results

[Swwils]

You burn the gas in a CCGT to make electricity for the heat pump.

We are ridiculously good at burning gas on site for heat, 90% is efficiency easy. So 1 unit of gas becomes 0.9 units of heat.

Even a crap heat pump turns 1 unit of electricity into 3 units of heat.

A CCGT powerplant gets 60% efficiency. So 1 unit of gas makes 0.6 units of electricity.

So, out 1 unit of gas made 0.6 units of electrical energy from the power station become 0.6*3=1.8 units of useful heat in the heat pump. Magically more useful energy than the gas itself had and superior to the, ridiculously good really, boiler.

If only we had some kind of reliable, large scale electrical base load power plant that didn't use gas or coal.

[MrPablo]

Glyn Hudson has done an update video on their heat pump install as well.

[Swwils]

Did he self install? That pump is running very well.

Goes to show that buffers is silly beans.

[Stinsy]

I think the point is to install the smallest HP you can get away with. That way it runs low-and slow through the shoulder months and flat out in winter. You need to consider how to provide additional heat on the very coldest days, this can be a wood burner, an A2A, or even resistive (eg storage heater).

[Ken]

I think the point is to install the smallest HP you can get away with. That way it runs low-and slow through the shoulder months and flat out in winter. You need to consider how to provide additional heat on the very coldest days, this can be a wood burner, an A2A, or even resistive (eg storage heater).

Dont modern modulating heat pumps do that anyway?

Thats what seemed odd about the deatails in that video that it did not seem to modulate. Modulating HPs have largely done away with the buffer/tank although i can see a case for them with small bore pipes therby allowing the HP to do its thing and the CH circuit its. I have a small bore CH and therefore ruled out HP and its not just the small bore but the different lengths of pipe from the manifold to the rads and the difficulty of balance that concerns me.

Both those in the videos showed how it should be done, MCS type assessments, upsize pipeing, upsize rads and commit to 24/7 heating. All this is on another planet for most of those considering retrofit especially her in doors.

[Stinsy]

I think the point is to install the smallest HP you can get away with. That way it runs low-and slow through the shoulder months and flat out in winter. You need to consider how to provide additional heat on the very coldest days, this can be a wood burner, an A2A, or even resistive (eg storage heater).

Dont modern modulating heat pumps do that anyway?

Thats what seemed odd about the deatails in that video that it did not seem to modulate. Modulating HPs have largely done away with the buffer/tank although i can see a case for them with small bore pipes therby allowing the HP to do its thing and the CH circuit its. I have a small bore CH and therefore ruled out HP and its not just the small bore but the different lengths of pipe from the manifold to the rads and the difficulty of balance that concerns me.

Both those in the videos showed how it should be done, MCS type assessments, upsize pipeing, upsize rads and commit to 24/7 heating. All this is on another planet for most of those considering retrofit especially her in doors.

Heat pumps typically modulate down to 25% of their max. When demand is less than that they cycle and throw CoP out the window.

[AGT]

He did a good self install video, his gas boiler was fed from47kg bottles and he installed a lot of monitoring( that’s his job)
Great instal and video to show it isn’t difficult to install if you design it first!!

[Oliver90owner]

I’m surprised the COP is so high. Does this include energy used to thaw the heat exchangers? Many installations include a resistive heater in the system, for very cold weather assistance, which may not be recorded/included for COP calculations

Calculations on COP are all very well, but while gas is less than a quarter of electrical energy (on standard current normal capped prices, these installations are little better than a good gas boiler system, from an economic POV. The main advantage is that, as renewables and nuclear (not at Hinkley point strike prices) reduce the amount of fossils burned, the CO2 emissions are reduced - good from a climate change POV.

I’m not yet sold on ASHP tecnology.

His heat pump runs in reverse to provide defrost cycles.

Does that provide a negative COP while it is doing that?

[Swwils]

Yes, a heat pump operating in reverse for a defrost cycle will effectively have a negative COP during that period.

Depending on the design you can either run the pump backwards or have just a simple resistive heater.

The defrost cycle only runs for a tiny fraction of the operating time so it's really not too much of an issue.

You must take care when talking about nodulation in heat pumps you need to be distinct between inverter compressor duty and variable refridgerrant flow.

All of the prerequisites should have been done in the 1970s like Europe did. UK as usual decades behind and grumpy people still installing micro bore to this day.

[Stinsy]

The UK’s moist, mild climate does no favours where defrost cycles are concerned. In very cold conditions the air is completely dry and no defrost is required.

Heat Pumps typically run in reverse to defrost the heat exchanger but additionally have a resistive heater in the bottom of the tray. This dramatically affects the CoP but the perfect conditions for freezing up (HP running full pelt in mild/moist weather) don’t happen very often, particularly if you use the pump as it should be used (247).