Air Source Heat Pumps

Baz@rr

Cheers guys.

Here's an update, not sure what it means...

We had the pump switched off at the mains and were barely using any electricity. I set main house thermostat too 19 and - this is the bit i think may be significant - left the heating and hot water controls set to the off position.

Now I'd think that the heaters, which were cold when I turned the pump back on should have stayed cold, as the heating controls were set to off.

And yet, 2 hours later they're blasting out heat and the thermostat is clicking off at 22 deg, despite having been set to 19.

Thinking about it, when we first came to see the house it was stiflingly hot and the landlord turned the rad stats off in the bedrooms then. Could it be some sort off working issue turning the heating on full as soon as the pump is going, and then ignoring the commands from the thermostat and the control panel?

At the moment its getting too warm and the pump is still working hard. I've turned thermostat down to 15 deg, but its clicking off at 23 now.

Interestingly the water temp in the storage cylinder has actually dropped a degree or two in the same time.

lovesgshp

Pity that I cannot post a load of graphs on performance for ASHP and GSHP. Unfortunately they are in PDF format. They cover only the IVT units, but are very interesting. ASHP to -20C, GSHP to -5C.

lovesgshp

Baz@rr wrote: »

Cheers guys.

Here's an update, not sure what it means...

We had the pump switched off at the mains and were barely using any electricity. I set main house thermostat too 19 and - this is the bit i think may be significant - left the heating and hot water controls set to the off position.

Now I'd think that the heaters, which were cold when I turned the pump back on should have stayed cold, as the heating controls were set to off.

And yet, 2 hours later they're blasting out heat and the thermostat is clicking off at 22 deg, despite having been set to 19.

Thinking about it, when we first came to see the house it was stiflingly hot and the landlord turned the rad stats off in the bedrooms then. Could it be some sort off working issue turning the heating on full as soon as the pump is going, and then ignoring the commands from the thermostat and the control panel?

At the moment its getting too warm and the pump is still working hard. I've turned thermostat down to 15 deg, but its clicking off at 23 now.

Interestingly the water temp in the storage cylinder has actually dropped a degree or two in the same time.

There seems to be some setup issue. If the thermostat is not switching off the pump at the temperature setting, then there looks to be a installation problem.

Baz@rr

Wow, just looked back and let me apologise now for the typos in my previous post. A combination of predictive text and not being able to see the full text box correctly. Nevertheless, I shall be sure to have myself flogged.

Anyway, temperature in the house is still 23 degrees according to the thermostat, despite being set at 15. Pump still cranking away, too. I must pick up a thermometer tomorrow to give me a better understanding of what's happening, but I reckon the house will continue to get warmer as the night goes on.

The controls upstairs look like this: http://i.ebayimg.com/t/Danfoss-FP715-Si-Central-Heating-Programmer-Matching-Room-Stat-thermostat-NR-/00/s/NzU5WDEwMjQ=/$T2eC16N,!yEE9s5jE,jcBQ!)MZ6sDg~~60_35.JPG

I can set different options for both hot water and heating - On, Off, Timed and All Day. Now, I'd have assumed that having heating set to "Off" would mean that regardless of what the thermostat in the downstairs hall was set to, the heating should not be kicking in. Setting a heater to "Off" should not result in it coming "On". That to me is the very definition of the word "Off". It's as if the word "Off" was created specifically for that very set of circumstances.

So we may have found the problem. Not only is it ignoring the "Off" part, it's also ignoring the "19 degrees" part. In fact, it's just ignoring me full stop and doing its own thing, like some wayward teenager. It's probably on drugs, in fact. And failing badly in school.

The plumber is coming out tomorrow to look at it, and to replace the faulty valve that resulted in water pouring through the ceiling. Someone from Grant is apparently coming down on Wednesday to look at it, too, so hopefully between them and with all the info you guys have provided, they'll be able to figure something out.

The fact the house is now smotheringly hot suggests the 8.73kW could well be up to the job though, doesn't it? Or am I missing something there?

albyota

OK, this latest info has identified some set-up / connection issues, and should hopefully resolve after Wednesday, however, this Grant system will eat electricity as the outside temperature decreases, keep an eye on it.

Good luck

AL

Baz@rr

albyota wrote: »

OK, this latest info has identified some set-up / connection issues, and should hopefully resolve after Wednesday, however, this Grant system will eat electricity as the outside temperature decreases, keep an eye on it.

Good luck

AL

Thanks! And don't worry, I won't be taking my eyes off the bloody thing.

I think I mentioned in a previous reply that there's a setting where the frost protection and immerser is turned off. Presumably that would save electricity, but then I'd guess it'd also bring the efficiency of the system right down so it barely produces any heat. Does that sound right?

albyota

Yep, if you turn off frost protection, and backup boost, the system will struggle to maintain temperature, and also risk damaging the heat exchanger, as you are up in the highlands, the temps are likely to drop and the output of the HPAW85 will reduce to about 5.6 kW at minus 5 with water flow at 45 degrees. So be careful what you adjust, I would advise you wait till Wednesday, but keep a log.

Baz@rr

albyota wrote: »

Yep, if you turn off frost protection, and backup boost, the system will struggle to maintain temperature, and also risk damaging the heat exchanger, as you are up in the highlands, the temps are likely to drop and the output of the HPAW85 will reduce to about 5.6 kW at minus 5 with water flow at 45 degrees. So be careful what you adjust, I would advise you wait till Wednesday, but keep a log.

Yeah, the missus has ordered me to stop mucking about with it and wait for someone who knows what they're doing to take a look at it.

Assuming such a person exists up here...

Thanks again for all your help everyone, it's hugely appreciated. I'll post back when I know more.

merlinonline

albyota wrote: »

Yes, unfortunately, this will also be a frost protection setting, this is, IMO one of the worst designs of heat pump, I have Mitsubishi Ecodan, no boost heater, it is inverter driven.

I need some advice about the Ecodan, its been fitted and is up and working but the electrician who knew everything about it wasn't about when it was commissioned and the plumber who did the commissioning didn't explain how use the settings in fact all he did say was "you won't need to touch anything in the airing cupboard, just use the thermostat in the hall"

It was only after swapping a PM on this site with Jeep Junkie that I became aware of that the night time setting wasn't being used.

Just to quote from the Householder info booklet, which I only discovered today! (apologies for copying it here but it may make sense of what I'm trying to understand).

Heating
The heating circuit within your home is controlled by two units, a timed programmer and a thermostat. The timed programmer will control when you want the heating to come on, and the thermostat will control the temperature.

Depending on the property and your lifestyle, the time clock pattern will need to be adjusted. If you are out of the property for most of the day and do not need heating at night, you may want the heating to come on in the morning and evening.

However if you are in most of the day and do prefer to keep the house warm at night, it should be more economical to leave the heating on continuously and let the thermostat manage the temperature. When doing this "night time set back" should also be used reducing the desired temperature down to 16-18 degrees C during night time hours. This ensures your house temperature stays at a comfortable level.

The heating pattern is individual to each property and may take a few weeks to get right just for you, but do be aware that if you set the thermostat extremely high or have the timed programmer to turn off and on continuously during the day, your electricity bills may be higher than is necessary.

So what we have is it being controlled by the thermostat only, last night it was set at around 19 degrees C and it was a mild night, as far as I know the unit didn't come on at all as the house maintained it temperature (mild night like I said) what seems to happen is when it is mild the system seems to hibernate, when I check the airing cupboard the CH light that says the unit is on is off and the nothing is displayed on the timed controller. When it is on the CH (red) light is on and also you get the normal econ display on the timed controller.

Is this "hibernating" the same as "having the timed programmer to turn off and on continuously during the day"?

The information supplied on operating is the only thing that is letting it down at the moment.

albyota

Hi, depends on your lifestyle, however, if you have a well insulated house, then using the programmable rom stat is IMO the best way to control it, I.e. setting the programmer to all day, and setting the room stat for different temperatures at different times of the day, for example... 10.30 pm set back to 16 for night time, the unit should not run, at 7.00 am set to 20. If your out all day set to 16. If your in set to 19 or 20. At 5.00pm set to 21. Obviously the heat pump cannot do domestic hot water and heating at the same time, so set hot water either for 6.00am for an hour, or 4.00 pm for an hour again depending on your lifestyle.
Hope this helps

AL