Not Happy with Air Source Heating

[Kev F]

Why do yours pull on immersion mate, mine don't as its unplugged can't say I've ever needed to go and plug it in either, we set a hw legionnaire programme for 2 hours once a week at 3am in morning. That's it immersion wise

 

[snb]

grants, daikins and most of the others i have worked on have a set up in the software that allows you to drop the flow temp down to as low as 15 degrees before it uses the electric booster. If you disconnect the booster the compressor will not kick in until the flow temp is above 15.

not sure how you get around the software on the samsungs as they also have the same setup

 

[kevobain]

Helllooooooooo

Ok in Scotland for an mcs install you would be designing a system so the unit runs to at least -5, me personally I'd design it to about -7, if customer had any data on actual average land temps of that area we could adjust the curve accordingly, lets start here

What's the unit?
You should have it programmed to run at 20c in day and no lower than 18c at night, its best to run 20c from morning to night with no off times during the day, the units I use come with a back up heater but we ALWAYS disable it as we don't like to use them as running costs can rocket.

Other factors t check is what was the underfloor loop set at ie 120mm centres or 200mm? If 120 great were onto a good start, if 200mm its ok. You want a flow temp from the unit set to about 45-47c max on Ufh. I'd personally if loops were 120 set it so my curve was from 37c in milder weather and 45c for days like now. This lets the weather comp kit control flow temps and I've found that pretty stable in most places. On your floor area your looking at 16kw unit.
If you can provide as much info as needed we can look deeper. I don't come on here much but I'm sure the lads will keep me informed

I think the first thing to say is that I don't think I had an MCS install. I looked in to it yesterday and it was just some random plumber and electrician who fitted my system. My builder/project manager subcontracted them in. I feel a bit like an idiot now, especially since I just found out about the available grant that I won't be getting as well!! The price of not doing your homework I guess. After reading what you wrote, I'm getting alarm bells about the whole installation now.

I'm not sure about the technical things you've asked about such as the centres on the underfloor heating loop. Is that the distance between the pipes? I'm not in the trade at all so am a bit thick about it. I have photos of the installation of the underfloor piping if that helps?

As for the settings, I'm offshore working at the moment so can't take a look but I'm pretty sure I have both the ATC and BTC controllers set up as per the Grant manual. http://www.grantuk.com/downloads/Grant-Air-Source-Heat-Pump-manual-DOC87-Rev05-January-2011.pdf
The settings are on pages 31 and 33. I have to admit to not understanding what much of the settings mean but I'd welcome some advice on whether or not I should set them differently. At the end of the day, whether the installer knew what they were doing or not, they never told me how to operate the system. The manual is all I had to go on and it's not the document ever written. I think the system might have a back up heater but I wouldn't have a clue how to switch it off or even if it's running and costing me money.

Thank you for the response mate. Sorry I can't get you much more information at the moment. I'm due home in a few days so should be able to find out more then. I do believe in the system but just can't seem to get it to work right. I'll persevere though. If another ASHP by a different manufacturer is the way to go, I may have to go down that avenue but obviously I'd prefer not to at this stage.

 

[kevobain]

On the note about high cost in winter you have to ignore that, you have to take a 12month period and then compare with other months, had a customer who was running a 5 bed house at nearly same cost as oil last winter, issue was it was colder than previous year and cost of elec had gone up he has his 12 month bill in, his oil would cost around £1600 a year, his whole house elec bill inc all his touch screen tvs and lights was £1300, he now understands its a 12 month look at prices and not a 3 month check. I've heard nothing but issues about the grant, so much so that people have taken out and put another in throwing units back at grant. Ashp can be very efficient even more so than natural gas, but they must be set up and sized correctly or they can cost twice as much as oil I've seen some horrendous installs and its getting a bad name because of theses installs.

The £200 a month figure is based on the last 12 months. From all the information I'm getting I can see that I'm just operating it wrong now. I'm interested in the whole 'don't switch it on and off' thing. My Economy 10 tariff gives me 3 periods of Off Peak energy a day. The heating and water is only set to come on during these periods. Are you advising that I should change my tariff to a standard anytime tariff and leave the heating and water to do it's thing for the whole day? I'd certainly much prefer that but wonder if it's a realistic option?

 

[kevobain]

have experienced high electric consumption before with people turning the system on and off.

you will need to run the air sorce for a minimum of 18 hours a day but preferable to leave it on 24hrs per day.

reason is purely the following.

when the heat pump first turns on it uses the immersion (direct electric element only 3 or 6kw) to get the flow above 15 degrees.

this is the period when it uses huge amounts of electric.

because you have underfloor it is possible when the system cools down slightly that you could be in a situation where the flow temp doesn't get above 15 for a couple of hours or more.


your electric tariff is also very high. change to single rate but you should get a good deal because of your high usage. don't expect to use less than 12000 kwh per year for heating but could be as high as 20000 kw/h

at present best to have heating on 24/7 and to time the hot water for the cheap periods. also change the underfloor temp to a lower temp from 11pm to 7am ( will reduce demand on air source unit when it is not as efficient due to colder outside temps.)

That sounds exactly like the advice I was fishing for in my last post. I have to admit that it seems counter-intuitive to make it cheaper by having it on for longer periods.

I wonder with my hot water if it needs to come on 3 times a day? We only normally have a couple of short showers and the occasional bath when my son is staying over. How long would a heat pump generally take to make enough hot water for that? I'm not sure about my tank immersion and if I should be only running it up once a week or something. I'm not even sure what it's set at now to be honest. I'll have to check when I get home.

Thanks for the good advice though. It's all hugely appreciated.

 

[Kev F]

Not sure how the grant works but the bigger manufacturers all use hot water priority, so as soon as the tank has water used it re heats it straight away. You need to make sure your heating is on all day ie 6am to 10pm at 20c, then set 10pm to 6am at 18c MINIMUM, this will keep the fabric of the house stable and you won't get any loss of heat at peak times. It's impossible to say without seeing it and its set up but something is definitely not right.

 

[kevobain]

Not sure how the grant works but the bigger manufacturers all use hot water priority, so as soon as the tank has water used it re heats it straight away. You need to make sure your heating is on all day ie 6am to 10pm at 20c, then set 10pm to 6am at 18c MINIMUM, this will keep the fabric of the house stable and you won't get any loss of heat at peak times. It's impossible to say without seeing it and its set up but something is definitely not right.

Thanks again Kev. I'm not sure if the Grant is hot water priority or not but I'll certainly try to find out. As far as putting the heating on all day - I'll try that out when I get home this week.

When you talk about setting the heating to 20c 6am to 10pm and 18c 10pm to 6am do you mean doing it on the individual room thermostats? The thermostats I have in my rooms downstairs have no timer function on them I don't think. Also, it would be difficult to set the temperatures upstairs because the radiators just have valves.

What I'm going to try and do is get some photos of the set up I have in the house, trying to get all the components in. I'll then post them on here to see if it helps.

The advice I've received on here is amazing. Thank you so much.

Kevin

 

[kevobain]

I'm home now from offshore just in time for some nasty weather. Oh well, better to be in the house than the North Sea. Anyhoo, now that I'm home, I've managed to get more information about my set up.

My ASHP is the Grant Aerona HPAW110 with 11.32kW output. It states a maximum heat output of 60c. I'm guessing that's only in the height of summer though.

This is the set up I have in my cupboard:

The switch on the left is the power to the heating timer which controls when the heating and water comes on and off. At the moment this is set so that the heating and water comes on 3 times a day during the off peak periods on my Economy 10 tariff.

I think the switch on the right is the immersion boost switch as it goes down to the HW booster kit. This was actually switched on this morning and probably has been on for a long time. From what I can understand, this switch overrides the immersion to make it come on even when not required - oops!! So, if my thermostat from the ASHP is set to 45c, the immersion should then set it to 60c? The cables protruding from the wall at the bottom of the picture are where the ATC controller used to be. It's now inside the pump itself because there was a wiring problem last year and the engineer couldn't get it back in the house without digging in to the walls!

This is what I have on the side of my tank:

Now can someone please tell me is the dial at the back the one which should be set to 45c or is it the immersion temp control which should be set to 60c? It was set to 65c when I went to look at it today!! Again - oops!! I opened the cover on the round thing at the front of the picture and it didn't have a temp control in it. Just a red switch thing which could be set to 1, 2 or 3 I think.

The final picture is the gubbings I have above the tank, none of which I really understand!

I'm hoping that the small changes I've made today make a difference. One question I still have though is the one about running the pump all day. Should I just set my timer in my cupboard to on all the time for the heating? I'm willing to try anything which might make it all work.

Cheers,

Kevin

 

[kevobain]

So anyway, as I said in my last post, I turned down the dial on the side of my tank to 45c and I switched off the boost switch thinking that I'd hopefully made a difference to my crazy costs. Well, as far as I know all I achieved was running out of hot water last night!!! Back to the drawing board I guess. I'm open to suggestions of what else to try.

Cheers,

Kevin

 

[Norcon]

Just rip the stoopid thing out and fit an oil boiler.

 

[kevobain]

Just rip the stoopid thing out and fit an oil boiler.

I can assure you mate, the thought has crossed my mind.
If I thought it was an easy enough conversion I'd probably even look at getting is priced up. I'm not going to let it beat me just yet though. I'm going to find out how to operate it properly if it kills me. I just got off the phone with Grant technical help and they told me to set the dial thingy to 45c and switch the boost switch on?!?! I'll give it a try to see if it makes a difference. He also suggested I get some programmable room thermostats to make it easier to leave the pump on all the time.

Anyone know anything about thermostats?!?!?!?!

 

[Agile]

I have skimmed through your posts and dont actually see what your main complaint is.

You seem to be sayiong ther house feels cold but even so you dont have your heating on for so many hours.

Its going to be far more expensive for you too if your local electricity is more expensive than the rest of the country.

One would have expected that you would have compared local fuel prices before choosing ASHP? But ASHP usually comes out well in high fuel cost areas.

You say you have rads upstairs. They need to be well sized to give enough heat output with a flow temp of only about 50 C.

It may help you if you can set your water heating to be only during off peak and have your heating on a lower setback temperature at night.

Tony

 

[Dan Robinson]

You're being very cantancerous (driving..can't spell) today Tony?

 

[kevobain]

I have skimmed through your posts and dont actually see what your main complaint is.

You seem to be sayiong ther house feels cold but even so you dont have your heating on for so many hours.

Its going to be far more expensive for you too if your local electricity is more expensive than the rest of the country.

One would have expected that you would have compared local fuel prices before choosing ASHP? But ASHP usually comes out well in high fuel cost areas.

You say you have rads upstairs. They need to be well sized to give enough heat output with a flow temp of only about 50 C.

It may help you if you can set your water heating to be only during off peak and have your heating on a lower setback temperature at night.

Tony

You're completely right. My main complaint is that my house is cold and I'm still paying a fortune for electricity. I wouldn't mind paying so much and having a lovely warm house. Alternatively, I wouldn't mind it being ridiculously cheap but not up to the standard of oil or gas central heating. What I grudge is the cold house and the cost.

It wasn't to complain that I came on here though, it was to try and get some advice on how I may be running my system wrongly. I realise that if I had the heating on all the time that my house would definitely be warmer but am worried about the cost being even more than it is already. From what I've heard so far though, I might give it a shot to see how it actually works out. I'm already recording my daily electricity usage so it wouldn't take too long to work out if I was saving or not.

The other thing I've asked since I've been on is whether it was possible to replace the ASHP with an oil system using the existing pipework and rads? That's a very extreme solution but I'd rather spend a bit of cash doing it now than wasting a tonne of money on an inefficient system. I just wanted to make sure there wasn't something else I could do to try and make the ASHP work better for me.

I hope that's made it clearer for you. Thanks for taking the time to comment on my post though.

Cheers,

Kevin

 

[SilentDancer]

Re the hot water

1) the temperature should be raised to 60ºC once a week to sterilise the cylinder.

2) Heat pumps aren't great for heating hot water as the required rise in temperature is greater than they can normally deliver particularly in cold weather. Grant do sell a hot water boost kit. http://www.grantuk.com/products/cylinders/grant-heat-pump-cylinders/ Is this part of your installation.

Domestic Hot Water Boost kit
Whilst it is possible to raise the DHW to 60ºC with an Aerona Air Source Heat Pump, it can be more efficient to set the hot water temperature between 45ºC and 50ºC and utilise Grant’s Domestic Hot Water Booster Kit to take the cylinder up to the desired higher temperature. This unit comprises an enclosure with 20A rated contactor, an override switch and relay, which works with the immersion element fitted in all Grant cylinders.

Re the heating

1) A lot of the problems with heat pumps stem from undersizing them. However, in your case I think the problems may relate to an over sized heat pump as you've a well insulated house. If the heat pump is oversized it cycles as reaches temperature quickly. Start up consumes a lot of electricity.

2) The installation should have a buffer vessel to minimise start ups.

3) The heat pump may be going into defrost mode a lot if the temperature has been cold. In such circumstances electricity consumption is high.

4) The heat pump is faulty.

5) The Grant units are Chinese made and have not been specified for UK climates and you can find numerous threads about problems with them such this one. http://www.ukplumbersforums.co.uk/renewable-energy/19157-grant-air-source-heat-pumps.html

6) Air source heat pumps aren't always as cheap as claimed. The EST did a study that found most installations they study has a COP of 2. You need a COP >2.7 to beat an oil boiler and if you are on mains gas they are a non-starter. This thread is a good summary of the issues. http://forums.moneysavingexpert.com/showthread.php?t=2968958

Personally I would rip it out and replace with an oil boiler. This would be easy to do you would just need to blend in to the underfoor circuit. I also think you should pursue the installer for recompense as the system clearly has not been set up/specified correctly