With gas boilers potentially being banned in new homes from 2025, should we look at alternatives now

mmmmikey · 13 October 2019 at 10:31PM

....again throwing round ideas but have you considered a biomass boiler as an alternative to a HP?

Reed_Richards · 13 October 2019 at 10:33PM

Pumping heat is like pumping water up a hill. The higher the hill the more power it takes to pump the water. Pumping heat, the bigger the temperature difference between where you pump the heat from and where you pump it to, the more power it takes. So an air source heat pump efficiency will vary a lot depending on the outside air temperature. The lower the air temperature, the lower the efficiency yet the higher demand for heat inside the house. In principle an ideal heat pump will always be at least as efficient as direct electric heating (an electric fan heater for example). But in practise some heat is lost from the refrigerant when it is outside the house and the worst-case scenario is that the pipes freeze and the heat pump stops working.

The ground acts like a big thermal store so if you dig down a little you find that the temperature varies less with the seasons than the air temperature.

Solarchaser · 13 October 2019 at 11:28PM

Would this allow you to more efficiently use an inline direct electric heater to boost the temp above the store temperature which is optimised for heat pump?

Yeah, generally you would be looking at heat pump to do bottom of cylinder and say a 3kw or 6kw element in the top.
https://www.advanceappliances.co.uk/product/47-electric-combination-boiler-ecb-210/

Something like that, is what I'll be going for.
I haven't decided if I'm opting for solar thermal for bottom ring, or just dual electric element using solar in summer and e7 overnight in winter.

I believe coastalwatch and possible Mmmmikey have bought this system already.
The link is for a 210 cylinder, but the company does a range of sizes.
They are very expensive for a hot water cylinder, but saves any contamination/legionella etc problems

Hexane · 14 October 2019 at 12:35AM

Cardew wrote: »

I don't know how many million families live in flats in UK, but for many of them Heat Pumps(all types) are impractical. Apart from the noise issue how do you mount and access the units on, say, a 20 storey block?

There are large blocks of flats in the USA and India that have air conditioning units on them. Have seen similar in Spain. They are ugly and presumably expensive to mount and to service, but they are fitted and they work.

Martyn1981 · 14 October 2019 at 7:35AM

1961Nick wrote: »

5 showers & 1 bath per day suggests a household of 6 persons & therefore a reasonably large house?

If the above is true, then 32000 kWh doesn't seem unreasonable.

For comparison, 3 of us managed to consume 27910 kWh of gas last year & we're already up to 17000 this year - now with just 2 of us.

Wowza - I simply can't comprehend that level of gas consumption. That's four to five times ours, despite a four bed house (loft conversion) and size for size, heating should go down with higher occupancy, not up. Have you considered closing windows and doors in the winter?

Martyn1981 · 14 October 2019 at 7:57AM

Hexane wrote: »

There are large blocks of flats in the USA and India that have air conditioning units on them. Have seen similar in Spain. They are ugly and presumably expensive to mount and to service, but they are fitted and they work.

I've got a friend who lives in an upstairs flat in terraced row (not quite a block of flats - but I'm getting there).

He has good loft insulation, only the front and back room have a single external wall, and 'underfloor heating' (the flat below him). He has basic leccy heating, and I have suggested a heat pump (small A/C unit), but heating is so little that it makes the economics questionable ..... but I am stressing the environmental gains from the COP.

Cardew · 14 October 2019 at 8:41AM

Hexane wrote: »

There are large blocks of flats in the USA and India that have air conditioning units on them. Have seen similar in Spain. They are ugly and presumably expensive to mount and to service, but they are fitted and they work.

I owned an apartment in a large block the USA with an Air to Air ASHP/air-conditioner. However like virtually every apartment block I have seen in the USA the design called for the units to be mounted on the flat roof.

A less than satisfactory solution is to have them on a balcony.

I stayed for one night in a single storey cheap motel near Boston that had an external unit. It was a disaster, noisy and the internal unit vibrated excessively.

To retro-fit to blocks of flats in UK would be impractical.

1961Nick · 14 October 2019 at 8:47AM

Martyn1981 wrote: »

Wowza - I simply can't comprehend that level of gas consumption. That's four to five times ours, despite a four bed house (loft conversion) and size for size, heating should go down with higher occupancy, not up. Have you considered closing windows and doors in the winter?

It's my next project now that electricity import is solved (75% reduction).

Gas consumption is split 9Mwh DHW, 18Mwh CH & I'm targeting a reduction to 20Mwh without any lifestyle changes. I'm hoping a new boiler & Hive thermostatic rad valves will get me there.

DHW is an issue because of the small cylinder size & the need for consecutive showers in the morning. To enable that, I'm running the boiler flow temperature & cylinder temperature considerably higher than is ideal.

roddydogs · 14 October 2019 at 9:21AM

No, because everyone knows that that date can't be met.

JKenH · 14 October 2019 at 9:30AM

1961Nick wrote: »

It's my next project now that electricity import is solved (75% reduction).

Sorry to hear about your divorce, Nick.:rotfl:

With gas boilers potentially being banned in new homes from 2025, should we look at alternatives now

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