UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

John_Pierpoint

grahamc2003 wrote: »

Sort of.

But the heatpump gives say 100kwh of heat inside for about 35kWh of electricity, whereas a gas boiler gives 100kWh of heat inside by burning about 110kWh of gas.

Cardew wrote: »

I can't see why that would be the case when they could have their gas boiler water temperature set to 50%

My point was that running an ASHP to give a water temperature of 50C gives a lower COP than, say, 35C.This is why heat pumps are so suited to under floor heating.

jeepjunkie wrote: »

It uses less than an electric shower

I think the overall figures suggest that 100 units of heat burned at the power station tend to arrive at the domestic consumer as 33 units of electricity, the other two thirds having been lost up the cooling tower and along the grid.
With modern gas turbines this efficiency can be over the 50% mark - so "burning" electricity in an efficient heat pump system and burning gas in an efficient condensing boiler produces a similar result overall.
Spending £300 on good draught proofing and insulation is far more sensible than spending £3,000 over-sizing the heat pump.

The DNO does need to be consulted about the heat pump and will try to extract money from you or the installer for the privilege.
An individual heat pump may be similar to a shower BUT for the following two points.

1. In an estate of houses with power showers no individual household will be running their shower continuously but with heat pumps they all could try to run the heat pumps continuously - The "community" of North Blyth were offered subsidised air source heat pumps and it cost £2,000 per household to upgrade the electricity supplies.

2. The DNO is likely to insist on yet another parameter in fitting the heat pump, the frequency it cycles on and off. Old compressors, with their high starting currents could "flicker" the lights, mess up internet connections, in fact my neighbour (a workshop about 100 meters away) installed a compressor - it took me some to time to realise that it was the compressor that could cause my earth leakage circuit breaker to turn off my supply :mad:.
I think a lot of progress is being made with efficient scroll compressors and soft start inverter motors to improve these problems.

http://www.decc.gov.uk/assets/decc/11/consultation/RHI/6453-rhi-consultation-domestic.pdf

I think there is a message here - if you want a heat pump do it soon to get the Renewable Heat Incentive, thus establishing "grandfather rights" to an electricity supply, without risking being caught up in another renewables "gold rush" and risk cowboy installers driven by commission.

Cardew wrote: »

It is also a fact that some(not all by any means) people who have paid good money for a product, are less inclined to be objective in their appraisal of that product.. Even on MSE tenants(both council/HOA and private) generally are more critical of heat pumps.

In theory all installers are meant to be trained, but from my experience of installing cavity wall insulation on 4 family homes and PV panels on my roof; the green technologies are still manned by get rich quick merchants driven by commission, selling to ignorant consumers.
If the industry expands rapidly, the average competence of its participants actually goes down.

What is needed is some sort of independent monitoring of performance against design
calculations and specification.

Cardew

John_Pierpoint wrote: »

I think there is a message here - if you want a heat pump do it soon to get the Renewable Heat Incentive, thus establishing "grandfather rights" to an electricity supply, without risking being caught up in another renewables "gold rush" and risk cowboy installers driven by commission.



In theory all installers are meant to be trained, but from my experience of installing cavity wall insulation on 4 family homes and PV panels on my roof; the green technologies are still manned by get rich quick merchants driven by commission, selling to ignorant consumers.
If the industry expands rapidly, the average competence of its participants actually goes down.

What is needed is some sort of independent monitoring of performance against design
calculations and specification.

My honest opinion is that in the UK, too many plumbers
(not all) have decided they are experts in the installation of these products
and have not really got a clue.

Totally agree, and the message I have been 'preaching' for the past few years. See:

https://forums.moneysavingexpert.com/discussion/2968958

Taking John's point about the 'cowboys' cashing in on the renewables 'gold rush', one only has to look at the solar industry.

Firstly 'solar thermal' was sold for unbelievable prices with even more unbelievable claims of savings. Paying many £thousands to save £tens a year at best. After several 'watchdog' type programmes and thousands of complaints to trading standards offices across the land, many of the cowboys switched seamlessly to Solar PV when the FIT scheme was announced.

Initially quotes of £18,000 to £20,000 for a 4kWp system were commonplace(when FIT was 40p+) now £5k to 6k for the same system is not difficult to find.

Obviously the price of panels and inverters have dropped a great deal, but nowhere near enough to account for a £12,000 to £14,000 reduction

[Deleted User]

Diallingtone wrote: »

Over the next few years, my aim is to generate as much electricity as I use - not necessarily at the time I need it, just an overall balance sheet. I can only achieve that with electric heating and, of the options available in that sector, ASHPs stand out as effective solutions.

That's my aim too... ASHP + solar PV. Plan to add Immersun after the festive period as it's a quick easy install. Unfortunately our terrain/location is not ideal for wind turbine so have complete schematics/plans to venture into hydro turbine from the river Got some bits already... It's an as and when project so there will be no regular updates.

Cheers

betsc

I'd like to ask for input on this. We had an Ecodan 14kw air source pump installed just as the weather got very cold. It seems to be less efficient than my oil boiler was, and is eating up 80 kwh of electricity every day!

Seems like a massive amount to me. Any comparisons available?

lovesgshp

betsc wrote: »

I'd like to ask for input on this. We had an Ecodan 14kw air source pump installed just as the weather got very cold. It seems to be less efficient than my oil boiler was, and is eating up 80 kwh of electricity every day!

Seems like a massive amount to me. Any comparisons available?

None of us can give any comparisons without a lot more info. House size, internal temperature setting, outside air temperature, rads/underfloor heating, insulation levels etc?

deano72_2

As geothermal said
1 set the target temp to 50c. That is still plenty hotter enough also from what I have come across this will eliminate faults aswell as they don't like target temps of 60c or even occasionaly 55c
2. Set the legionella cycle to 1 in every 150 cycle which will save pointless energy being used

betsc

Geotherm wrote: »

None of us can give any comparisons without a lot more info. House size, internal temperature setting, outside air temperature, rads/underfloor heating, insulation levels etc?

I am ashamed to say i don't know the suqare footage, but it's a 1998 barn conversion with a lot of glass. 70% is underfloor heating - and the rest is an old cottage with thick walls which was incorporated into the house by being joined to the barn. I keep the cottage part of the house shut off and at a temerature of 16 degrees unless there are visitors staying, which there haven't been. Temperatures have been around zero degrees for the last 3 days,

lovesgshp

What have you got the inside temperature set at and the domestic hot water?

John_Pierpoint

betsc wrote: »

I am ashamed to say i don't know the square footage, but it's a 1998 barn conversion with a lot of glass. 70% is underfloor heating Temperatures have been around zero degrees for the last 3 days,

I think we will be getting into a discussion about the orientation of the windows (they can be over all "U" positive - capturing more heat in the day time than they lose over night) plus their technical design and "curtains".
What sort of "barn" is it - timber frame stuffed with "Celotex" ? or massive slabs of granite?

Then there is the subject of how you or your better half are trying to "control" the heating.

Does the building have any SAP (Standard Assessment Procedure) paperwork covering its thermal envelope and energy requirement?

[I have a contact, with pots of money, where the Ice Energy "surveyor" was suggesting the installation of a heat pump into a medieval hall house with a gas main available in the street outside]

[Deleted User]

betsc wrote: »

I'd like to ask for input on this. We had an Ecodan 14kw air source pump installed just as the weather got very cold. It seems to be less efficient than my oil boiler was, and is eating up 80 kwh of electricity every day!

Seems like a massive amount to me. Any comparisons available?

What are your running times, house size, target temps etc. If it has just been installed then have the installers been back to check, tweak etc?

But on the face of it for a single 14kw Ecodan to rack up that much daily it must be running quite hard for very long periods... Would be a big concen to me if it was working that hard. Where is the heat going?

Ours runs 5:30 to 9:30 then 17:30 to 21:30 with two DHW cycles weekdays. At weekends it is on from 5:30 to 21:30 all day again with two DHW cycles. These running times produce a weekly average of roughly 40 units daily in freezing conditions. In milder conditions it could be as low as 10 units daily. I hope i have explained that ok [figures are for whole house consumption]? Heat is topped up at night in the livingroom with WBS.