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

matelodave

Perhaps it's because the government has procrastinated about it for so long that no one really believes that it will happen.


Originally the RHI was due to be implemented for ASHPs and other renewables about 3 years ago and was to run for approx. 16 years, it's been put back several times and now they are suggesting that it will start in March 2014, but will now only be paid for seven years and initially only for new installations - which will still be better than nothing but I'm not sure if it includes new builds - it might just be for retrofits.
Existing installations which were fitted after 19th July 2009 are supposed to be included sometime later this year - although I'll believe it when I see it (my installation was Sept 2010 and I'm still waiting to find out what I've got to do to qualify)


There is also a Renewable Heat Premium Payment which is an up-front grant and was to fill the gap until the RHI gets implemented. Any payment you get from the RHPP which taken off any RHI that you might get. The RHPP ceases in March 2014 when the RHI comes in. Again I'm not sure if it applies to new builds. It's worth checking because there are some strange rules about new builds & self builds - I think self builds might be eligible but new builds aren't - you need to read the rules very carefully to determine what the difference is.


Grean Deal is just a way of financing an upgrade at not very favourable terms, over a long period and means that if you move the new owner takes over the remaining debt. Probably not a good idea for most people - a bank loan or extension to the mortgage is probably cheaper and you have fewer hoops to jump through

richardc1983

Hello everyone...

So this thread has been running for 5 years exactly today! How time passes us by.

I am enquiring for a friend who has now had a Samsung air to water heat pump installed. This is to heat the hot water and radiators (no UFH) My friend is experiencing high installation costs - £145 for the month of December. As you know we have had a pretty mild winter so far. The installers have set it to run at 50C flow temp through the radiators with one disinfection cycle running on a Tuesday once per week. I've recommended to try running it at 45 or even 40C if possible?

Radiators in some rooms have been replaced for larger radiators or doubled up...

Control wise the installers left them with no operating instructions or anything so they currently just carry round a wireless thermostat and place it in the living room or bedroom and set it down to 18C at night and put it upto 19/20C during the day/evening. All radiators have TRV's fitted which currently are all on max... the installers have said all the radiators are getting upto the desired temperature. When the system is running my friend is happy the house seems to be warm enough although when I have been round rooms do feel cold but I don't think they like the house too warm

I've told them they need to leave it operating 24/7... however considering this post is now 5 years old... could we possibly have a list of "optimal operating procedures/settings" that we have learnt over this period for an Air to Water system that is only using radiators and not UFH? To go back through all the posts it is going to take a very long time. I could perhaps add this to the first post in the thread for ease of future reference.

Where is the best place for the room thermostat to be placed especially if wireless? The installers have said the hallway.

Optimal flow temps, what are these? 40-45C or even 50C like the installers set it at?

Immersion heaters on the Samsung EHS system when will these kick in? Especially given the current mild UK temps?

Any more tips.

Regards
Richard.

matelodave

Most heatpumps are specified to work at 35 degrees and I read somewhere that every degree above that increases the cost of running it by about 2,5% so the lower the temp you can run the system the better. A 50 degree flow temperature could therefore cost 37.5% more than 35 degrees, just by reducing it by 5 degrees could reduce your consumption by 12.5%


It shouldn't be too hard to get operating, installation and commissioning instructions from the internet which would help with tweaking it. You can also then see if they are running the system on the edge of the booster heater, like wise, at what temperature are they keep the hot tank. The lower the temp the better otherwise the immersion might be kicking in. Check the temperatures where the heaters cut in and try to run the system below that.


I run my system with weather compensation which means that the unit only winds up it's temperature when it cold and reduces it when it's warmer. If you can optimise your flow temperature to match the house heat loss you should be able to reduce the running costs a bit. If you need 50 degrees when it's zero outside you should be able to get away with 40 degrees when it's plus 10.


Do some heatloss calculations for each room and check the radiator sizing for the flow temperatures that you are using and add them together to make sure that the unit is big enough to heat the place without flogging its heart out.
It took me a couple of winters to tweak mine but it's now pretty well optimised - we've used 500kwh less this December than last and 600kwh less this January compared with last years. That's a saving of over £120 over the same period last year

richardc1983

Thanks for that. Yeah what temperatures do you keep the house at during the day and then at night?

matelodave

We've got u'f heating so we can have the internal temperatures a bit lower than most people as the room temperatures are very even, no hot or cold areas. The lounge is 19, bedrooms, hall and kitchen are 17, study & bathroom are 18. We set them back by 3 degrees overnight and the heatpump reduces by 5 degrees as well between 10pm and 6am). Each room has its own programmable thermostat
My flow temperature is 25 degrees when its 15 outside and 42 when its -5 so it generally sits at about 30-35 degrees. Like wise my hot water tank temperature is set to 45 degrees. My back-up heater won't come on unless the outside temp is below -5 and the hot water tank immersion heater only comes on for the sterilising boost to 65 degrees once a week. Our calculated house heat requirement is 9.8kw and we've got an 11kw heatpump.

[Deleted User]

matelodave wrote: »

We've got u'f heating so we can have the internal temperatures a bit lower than most people as the room temperatures are very even, no hot or cold areas. The lounge is 19, bedrooms, hall and kitchen are 17, study & bathroom are 18. We set them back by 3 degrees overnight and the heatpump reduces by 5 degrees as well between 10pm and 6am). Each room has its own programmable thermostat
My flow temperature is 25 degrees when its 15 outside and 42 when its -5 so it generally sits at about 30-35 degrees. Like wise my hot water tank temperature is set to 45 degrees. My back-up heater won't come on unless the outside temp is below -5 and the hot water tank immersion heater only comes on for the sterilising boost to 65 degrees once a week. Our calculated house heat requirement is 9.8kw and we've got an 11kw heatpump.

Sounds Baltic :snow_laug

richardc1983

I guess you have lower room temps as it's very even so no cold draughts or cold spots?

matelodave

That's right - the tiled bathroom & kitchen floors are nice & warm with bare feet, so is the laminate floor in the hall and all the other rooms are carpeted. There are virtually no draughts and those that we've got have been warmed up by the warm floor. There's a towel rail in the bathroom that heats up when the heating or hot water is being heated.
We've got our sterilisation boost at lunchtime on Saturday, working on the premis that the outside air temperature is a lot warmer at lunchtime than it is at 3am so the h/p doesn't have to work so hard.


I have tweaked my system myself to optimise it to suit how we use the system (it's a bit different to the way it was set up by the installer) I've also adjusted the weather compensation & equilibrium point so that the heaters only come on when either manually required or when the outside temperature is below -5. Ideally you only want the immersion heater to kick in for the sterilisation cycle - when ours does, the increased water temperature lasts us from Saturday lunchtime right through to Monday morning so it doesn't really compromise the system efficiency as the tank doesn't need any heat on Sundays.
Our Daikin system looks to be less complex than the Samsung & Mitsi systems insofar as there is only one pump and one motorised valve rather than the Gledhill cylinder with all the gubbins attached

richardc1983

Ok going to have a look at this system later on need to find a manual somewhere for the controls but I can't find one online.

So I'm going to try with flow temp of 40c, what should the hot water be set at? Also do you think it's worth setting sterilisation cycle for a Saturday & at what time?

Anything else, where should the EPH wireless thermostat go?

Air conditoning and air to air is my forte.

zeupater

richardc1983 wrote: »

... where should the EPH wireless thermostat go? ....

Hi Richard

I would say that the logical location would be in a 'non-living' area such as a hallway so that other intermittent heat sources (body temperature, TVs, cooking etc) don't skew the readings and affect the heating level/pattern - it should also be in an area without other thermostatic controls so that the reading isn't overridden and the rest of the house is overheated .... going even further, wherever the wireless thermostat is located, it would make sense to leave it there in order to maintain consistancy.

HTH
Z