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

richardc1983

jeepjunkie wrote: »

Hi Richard,


I don't have any flow temp figures to hand right now but can offer this information.


Weekdays: 05:30am to 08:30am 21c - I get up early ;-)
Weekdays: 5:00pm to 09:30pm 21c
Set back to 17c outwith


Weekends: 06:30am to 9:30pm 21c


Set back to 17c outwith


DHW set to 50c however...as the solar immersion generally boosts way higher than this the there is no need for e.g. weekly boost to 60c for disinfection purposes.


In the real world... with the wife working part time the system is usually on all day on two of the weekdays and of course on all day on school hols :-( Not bothered as long as its sunny :-)

Running costs... 5th December 2014 to 7th January 2015 ~£144 with solar panels covered in snow for some of that time.
Cheers


Colin

Outside of set back the system is set for 20c and she is happy with that temp, she knows how to adjust the hall thermostat if needed.

Could do with knowing your flow temps and whether you have underfloor or rads.

richardc1983

jeepjunkie wrote: »

Hmmm...


2C outside and our flow temp is 38C. Outside unit just emitting a woosh of air unlike noisy oil boilers flu. Our Ecodan is happy down to -25C without immersion backup. Being rural Scotland we have had -16 with no issues heating a 100+ year old detatched house.


Not sure where you get your information...?

What's your heating curve set to I.e max and min flow temps will control to based on the outside temp. The Samsung system I speak of will use the max temp at -2c but for Scotland it says to set it for -6c.

[Deleted User]

richardc1983 wrote: »

What's your heating curve set to I.e max and min flow temps will control to based on the outside temp. The Samsung system I speak of will use the max temp at -2c but for Scotland it says to set it for -6c.

Will find out tonight. Cheers

richardc1983

Thanking you

richardc1983

matelodave wrote: »

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.

Out of interest what was your weather compensation set at before. The Samsung I am looking at is set to -2c by samsungs recommendation but in Scotland they reccomend -6c... Not sure why? Houses are the same up there are they not?

lovesgshp

richardc1983 wrote: »

My partners mum has a Samsung ehs heat pump and it was set for a max flow temp of 50c under compensation. She's had a bill for 400 for two months. Temp is at 20c during timed on and night set back to 19c it runs for about 8 hours a day during the timed on periods. We're getting no where it's the company that installed it they have been out and recommisioned it made a right hash of it, there was zero pressure in the system and the radiators were cold half of them because they haven't bled them of filled the system properly. All rads had their balancing valves fully open so some rads further away were stone cold, I've balanced the system properly and we're getting a 10c drop between the send and return flow temps.

I sorted the above yesterday as I decided enough was enough. Her husband is in his last year of terminal cancer and she is sat in a coat in the house, the stupid install company are useless and don't care. Even though it's never worked properly in the 2 years it's been in with extortionate energy bills. I've adjusted the max flow temp to 45c and the house is still toasty. Theres a +-5c option where the user can increase or decrease the flow temp. I've turned it down to -5c so flow temp is now 40c and rads still nice and warm. This morning the unit has used £1.04 since midnight rather than the £3.50 it would have used. She's a fan convector in the kitchen which also helps to put heat into the house quite efficiently. Is there anything else we can do to optimise this system, I am thinking of trying max flow temp at 40c if house is warm enough meaning at -5c setting flow temp will be about 35c. It is tweaking it now and as I work in this area in HVAC I have a full understanding. Hot water cylinder temp is 48c and the system is set to use no immersions at all apart from the weekly boost to 60c for disinfection purposes.

Heat curve is set at outside temp of -2c as per Samsungs suggestion but it also suggested setting it for -6c for Scotland? Any reason for this? Surely -6c would be better as your giving it more scope to adjust down and be more efficient.

Regards
Richard

Can you give me the heat curves for the system as that would help, also is there a buffer tank?

richardc1983

No buffer tank. I've since changed the heat curve after I wrote that post. The heat curve is a straight line. Originally at -2c the flow temp would be 50c and at +15c it would be 37c. Rads were too warm and they are massive so unit constantly cycling off. I've changed it the other day to -6c @ 45c and +15c @ 32c - since then electric usage has halved but I'm sure we can improve it. I can send you a graph of the heat curve I have re-drawn. Here is a user manual... http://www.samsung-heatpumps.co.uk/pdfs/User%20Manuals/EHS%20User%20Manual%20v2.pdf

lovesgshp

richardc1983 wrote: »

No buffer tank. I've since changed the heat curve after I wrote that post. The heat curve is a straight line. Originally at -2c the flow temp would be 50c and at +15c it would be 37c. Rads were too warm and they are massive so unit constantly cycling off. I've changed it the other day to -6c @ 45c and +15c @ 32c - since then electric usage has halved but I'm sure we can improve it. I can send you a graph of the heat curve I have re-drawn. Here is a user manual... http://www.samsung-heatpumps.co.uk/pdfs/User%20Manuals/EHS%20User%20Manual%20v2.pdf

Thanks for the manual. It is quite a complicated one with so many settings, so need to spend some time looking at it.
The heat curve influence from perhaps the indoor sensor could be too high, but it looks like you are going the right way with the measures you have already taken. Phase the temperatures up, in relation to the outdoor temp.
Also check the peak DHW temp and make sure it is not too frequent.
Yes, please post the heat curve graph.

richardc1983

lovesgshp wrote: »

Thanks for the manual. It is quite a complicated one with so many settings, so need to spend some time looking at it.
The heat curve influence from perhaps the indoor sensor could be too high, but it looks like you are going the right way with the measures you have already taken. Phase the temperatures up, in relation to the outdoor temp.
Also check the peak DHW temp and make sure it is not too frequent.
Yes, please post the heat curve graph.

Yes it is a complicated one. The hot water peak temp is 48c with a drop of 5c before hot water is reheated. We have set it so that it will not use the immersion for water heating and the backup heater in the outdoor unit has been disconnected by the manufacturer as it is not used over here in the uk.

The unit does not work with the indoor sensor on the weather curve, that literally sends a run on signal on or off. It's the outdoor sensor it works with for determining flow temp.

Here is the graph we're on the blue line at -6c.

richardc1983

lovesgshp wrote: »

Thanks for the manual. It is quite a complicated one with so many settings, so need to spend some time looking at it.

I could also email you the updated manual I got from Samsung EHS that explains some things in clearer derail although it's a condensed down version.