Air Source Heat Pumps

zeupater

Cardew wrote: »

However in post #1553 'air source heat pump man' posted:



The brochure states 'When converting this off grid barn' .

The term 'off-grid' is surely only used to mean off the electricity grid. you would hardly expect a house high up on the remote Moorland to have mains gas.

Hi

When you drill down to the datasheet for the heat-pump, the case study which references this particular building doesn't mention off-grid at all ... simply concentrating on being carbon-neutral ... (http://www.globalenergysystems.co.uk/_files/downloads/products/Data-Stirling.pdf)
... without having a grid connection the property would need some form of electricity generation other than the pv, with all of those hills and a water source being available I wouldn't be too surprised to find a small scale hydro-turbine operating nearby, however, there doesn't seem to be any evidence in the photographs of anything other than the monobloc heat-pump and the log-burner ... the only real alternative would be a generator set, but that would mean that the entire case-study and all of the claims are totally misleading ....

... I reckon that the HP datasheet case-study(#2) is correct as there's no reference to off-grid, therefore the pv is simply offsetting the carbon-fuel consumption of the heat-pump .... it's the only sensible interpretation.

HTH
Z

gterr

hebridean wrote: »

I'm currently on an economy 10 tariff with the Scottish Hydro and the peak/off peak units are working out about the same. I run the ashp at this time of the year during the cheap rate times and will run it all the time when the weather turns colder.
Yesterday i tried getting quotes for the economy 10 rate and found it wasn't possible online and phoned a couple of companies, E.ON and EDF. Both were cheaper than the Hydro and i would save about £150 on the year if i changed. However if i add up my peak and off peak units and use this total i have found that i could save another £100, but i would have to change the meter etc.
So how are you good people on this forum running your ashp's by way of electrical supply?

Many thanks

Hi Heb,


Sorry to dig this up from ages ago, but I haven't been on the forum recently.


We were initially on Economy 10 for our ASHP, but when Hydro announced big price rises (a couple of years ago) we tried to shop around for other Eco 10 providers, and had no joy. Then I did the calcs based on actual kWh usage per year, plugged the data into a comparison site and concluded we could do much better if we swapped the meter for a standard one and went for a fix. We are with EDF Energy on a 2+ year fix. Our consumption is similar, but we pay less. Also, we now have the advantage that we can use other appliances whenever we wish, not needing to wait for the Eco 10 hours.


Just do the calculations. You need the actual kWh for your last 12 months or so.


Oh yes, and Hydro swapped the meter to a standard one without charge.


Hope this helps!

lenny53

I Have a Mitsubishi Heat Pump Boiler fitted to my housing !!! home ,when the system work it was great , but after it was serviced by the housing !!! contracted service agent our electric bill rose dramatically to £1290 over a warm 3 month period , the bill is still being paid of in instalments and the heating system turned off now 90% of the time , I'am of the belief that the service agents are working behind the curve when working with more up to date heating systems , The engineer we had to service our system was a gas service engineer with virtually no experience with Air source systems , clearly a case of housing assoc awarding contracts to the lowest bidder rather than there quality of service .
sorry for the rant but needed to let of some steam

matelodave

It's a bit late now, but it's always a good idea to write down all the settings so you can put it back to rights after a bit of ill advised tweaking.

It sounds as though the settings have been changed - possibly back to the default ones which may not be appropriate
Perhaps you need to get hold of the operation & installation manuals to check out all the settings

I can't offer any help as I've got a Daikin which I checked when it was installed. I've done some tweaking myself to optimise it, carefully keeping a record of what I did and what effect it had.
It's also best just to adjust one parameter at a time to see what happens.

zeupater

Regarding the price charged ("There is no way anyone should be charging that sort of money as the trade price of the heat pump is less than a one third of the price you have been charged ") ... this is really a major issue in the current UK market which needs to be addressed by the manufacturers if the technology is going to be considered as being mainstream at any time in the near-future.

I, for one, am completely amazed by the installed costs which are mentioned on these boards ... seemingly, even on a basic retrofit install, a ~£3k unit costs £6k to install (ie £9k installed) ... pretty odd when it should technically be little different to a replacement gas boiler install ... a few pipes, some wires, drill a couple of holes, screw some screws, setup, test & commission .... don't you just love the approach of UK business to margins (greed vs business acumen) .... perhaps it's time for the manufacturers and major trade bodies to take the lead and publish unit costs and a realistic target install cost ....

HTH
Z

Cardew

In addition to Zeupater's post above, surely your post sums up IMO the problem with the Heat Pump 'industry' in UK.

I don't know if your firm participated in either phase of the EST trial, but you are doubtless aware of the results, and the conclusion that the correct installation in a suitable property is crucial to acceptable performance.

However good your product might be, by selling them through 'Jewsons' or similar outlets you have no control over the installation firm.

There are 'cowboys' operating everywhere in UK and it appears that all the heat pump manufacturers just sell their products to anyone and take no responsibility for a subsequent poor installation.

Indeed you say you would ensure that your units would not be sold and installed by the firm who apparently charged £19,000. How would you achieve that aim for all outlets and installation firms?

With a house totally unsuitable for a heat pump, how many installation firms would refuse to quote me for an installation? Not many I wager!

Until Heat pump manufacturers take real responsibility for the installation of their products, as well as quoting and guaranteeing realistic 'system' COP figures; the public should be sceptical about the whole industry.

P.S.
Please don't quote MCS are some sort of guarantee of performance - it aint.

Robwiz

This is not true just for heat pump installers, but biomass too.

Installation labour charges are highly inflated and vendors typically suggest the most expensive boiler they can cost-justify in relation to the projected RHI payments.

Cardew

Cardew wrote: »

In addition to Zeupater's post above, surely your post sums up IMO the problem with the Heat Pump 'industry' in UK.

I don't know if your firm participated in either phase of the EST trial, but you are doubtless aware of the results, and the conclusion that the correct installation in a suitable property is crucial to acceptable performance.

However good your product might be, by selling them through 'Jewsons' or similar outlets you have no control over the installation firm.

There are 'cowboys' operating everywhere in UK and it appears that all the heat pump manufacturers just sell their products to anyone and take no responsibility for a subsequent poor installation.

Indeed you say you would ensure that your units would not be sold and installed by the firm who apparently charged £19,000. How would you achieve that aim for all outlets and installation firms?

With a house totally unsuitable for a heat pump, how many installation firms would refuse to quote me for an installation? Not many I wager!

Until Heat pump manufacturers take real responsibility for the installation of their products, as well as quoting and guaranteeing realistic 'system' COP figures; the public should be sceptical about the whole industry.

P.S.
Please don't quote MCS are some sort of guarantee of performance - it aint.

The above quote refers to a deleted post by someone who claimed to be the Managing Director of an ASHP manufacturer. He obviously didn't ask MSE's permission to post in his 'official' capacity.


The thread below deals with some of the tactics used by installers to 'extort' money for mandatory servicing of heat pumps.


https://forums.moneysavingexpert.com/discussion/4641311


It is yet another case of ASHP manufacturers apparently exercising no control of firms installing their products!

andy2308

Hi,

I've been living with a Mitsubishi Ecodan system now for nearly 3 years, our house was a new build with this system installed.

After weighing up the pro's and con's, I'm seriously considering ripping the system out and going back to a combi.

Pro's:

Running costs, when running in its eco mode and not having to work hard it does save money - particularly in summer months when you're only using hot water. However the running costs could also be attributed to the fact that the house was built and insulated to a very high standard to accommodate the parameters of the system.

And now the cons as I see them:

1. Space - lack of. Bloomin' massive storage tank in the airing cupboard means there's absolutely no room for any storage and can't be used as an airing cupboard. Also factor in that you'll need to locate the outdoor unit somewhere and it needs to be spaced away from the property to allow adequate airflow around it. It's not small either and the larger the house, the bigger the outside unit.

2. Noise - I can honestly say it drives me nuts! The outdoor unit is outside the patio door to the living room. The compressor & fan are variable speed. When it's not working too hard it's not obtrusive but when it cranks up it really drones at a pitch that really goes through you! I have it set for a hot water cycle in the early hours and if I'm awake I can even hear it in bed, and our bedroom is the opposite side of the house!

3. Performance - Use it in its ECO mode and it'll just about manage 22C provided it's not too cold outside, when the outside temperature drops it makes the rads hotter, the upstairs rooms are actually warmer on colder days. You can override ECO, if you do it costs a bomb to run.

4. Lukewarm radiators - Now that doesn't bother me but it really bothers the lady of the house who likes to warm herself on the rads on a cold day. You can't really do that! You see the radiators are all oversized to accommodate the lower running temperatures so forget having a quick warm up.

5. Timings - This is a right pain in the *rse. You see you can't have hot water and heating at the same time. Priority goes to hot water first. This means that when it's really, really cold and you happen to be at home all day, you've got to allow sufficient time with no heating on so that it can heat the water sufficiently. Budget for an hour or so at least to top up the hot water before you get your heating back, by which time the temperature has dropped!

If you've got friends or relatives staying then make sure you program in extra time for hot water or you'll be using the booster immersion, or bathing in cold water!

6. Anti-legionella - This has been a total and utter nightmare on ours from day one. After much tweaking of settings the legionella control seems to work but the immersion has a mind of its own. Basically the system will just switch over to immersion heating after about 30 minutes of heat pump. I know this because when I'm at home working I'm suddenly alerted to the sound akin to a large kettle trying to boil in the cupboard behind me. Turn off and on again and it reverts to heat pump control. Basically any savings I make on the heat pump system I lose through use of the immersion. You can of course isolate the immersion - then it just sits and waits, then you end up showering in lukewarm water.

As a trained refrigeration engineer and gadget freak I wanted to love this system. The principle is sound, I just don't think the technology - based on this system - is there just yet. There's been more than a few visits from various people to look at this thing and lots of head scratching.

We've been told that these work better with underfloor heating.

Cheers,

Andy.

Robwiz

I can understand your frustration – your experience proves that ASHPs can under perform if there are issues with design, installation and operation. I'm not a fan of ASHP (in my view an overly complex, expensive way of home heating) but there's no reason why yours should be so unsatisfactory.

1) Space - depending on the size and layout of your house you could find a gas combi just as frustrating – the time for hot water to reach the tap, inability to use two hot taps at the same time, insufficient flow for showers, etc.

2) Noise - not good. Our AAHP is very quiet outside and inaudible indoors. Has your outdoor unit been installed correctly on anti-vibration feet? I would re-programme the system so that it doesn't run overnight as much as possible.

3) This sounds like a set-up/control issue. We found that even with TRVs fitted to the bedroom radiators in our gas CH system we wasted heat unnecessarily heating the bedrooms when not needed. Can you turn them down/off? There should be separate zone controls for upstairs and downstairs.

4) Lukewarm radiators - sounds like you have weather compensation. This is actually the most energy efficient way to heat a home - the control system balances heat input with the heat lost by the house by tracking the outside temperature.

5) Timings - everything I've read suggests that using ASHP for heating and DHW introduces compromises. I would be tempted to use a conventional immersion heater for DHW and restrict the ASHP to space heating duties only. The efficiency drops right off as the pump raises the water temperature towards its theoretical maximum of 55ºC. For a family of four we use less than 6 kWh electricity per day to heat all our water using a traditional immersion element in the hot water cylinder. That's less than £1 per day. We then use the CH for heating the house on time setting that match our occupancy. If your house is getting uncomfortably cool in one hour then I would take a look at its air tightness. A well-insulated, modern home shouldn't lose heat that quickly.

6) Anti-legionella – see 5 – bin the ASHP for DHW and use an immersion heater on a time switch instead.

Underfloor heating shouldn't make much difference if your ASHP and radiators are properly sized. The system would work in the same way, introducing only as much heat as needed to balance the heat lost through floor, walls, windows and roof.