Air Source Heat Pumps

Cardew

gterr wrote: »

I have also been observing the control panel closely. When the compressor and fan are on the hot water temp rises a few degrees beyond the normal 51 C : maybe to about 55 or 56 C.

Presumably built into the program is provision to raise the water to 65C(by immersion heater?) every X days to prevent Legionnaire's Disease?

gterr

Cardew: Yes, factory setting is to raise it to 65C once a week. To do this the auxilliary heater is used. I have just changed the setting so that it does this at a time when I have off-peak electricity ( we are on Economy 10).

Strangely, although I can set how many times a week this occurs, and at which time of day, I can't actually see which day of the week this will be. I'll just have to look at the control panel every morning and see which day the water temp is high. (This would be a good time to have a hot bath, wouldn't it?)

zeupater

gterr wrote: »

..... I have also been observing the control panel closely. When the compressor and fan are on the hot water temp rises a few degrees beyond the normal 51 C : maybe to about 55 or 56 C. Then the compressor and fan switch off, after which there is a brief surge in both the hot water temp, and the flow temp (flow temp rose to about 45C briefly). This is reflected in the rad temperatures: a brief surge in temp before falling back to 25 C or so. Before I made today's adjustments to the computer the ONLY time the rad got even slightly warm was during these brief surges in flow temp.

Hi

I expect this is as the hot water cylinder reaches temperature the flow temperature is at high temperature when the valve switches back to the heating circuit, that's why I posted ....

Another thought is that the 'tepid' heat is a a by-product of the system heating the domestic hot water and everything is working at the required temperatures .... this is why it would still be an idea to know what both the temperature described as 'tepid' and the normal temperature of the radiators actually are ...

It would probably be a good idea to monitor the system for a while and if all is okay look at adjusting the internal temperature sensor settings so that the system works in an 'intelligent' way .... perhaps your installer or WB could provide guidance on this ...

HTH
Z

gterr

zeupater wrote: »

It would probably be a good idea to monitor the system for a while and if all is okay look at adjusting the internal temperature sensor settings so that the system works in an 'intelligent' way .... perhaps your installer or WB could provide guidance on this ...

HTH
Z

Thanks for that. (I am sort-of hoping that the system will now work intelligently without further intervention from me!):)

gterr

Geotherm wrote: »

Gterr
Are there any alarms recorded on the pump menu?

Sorry, Geotherm, I missed this post.

I have looked at the alarm log. There isn't much there. A few "Tripped motor cut-out compressor or phase fault" and similar "... fan fault" from the time when the system was first switched on by installer, and similar later when we had the electrician back because a circuit kept tripping. Nothing since May 2011.

gterr

Another question if I may (especially for Geotherm if he's reading).

We are on Economy 10 tariff but at the moment we are using more peak rate units than off-peak units. I'm sure this is the pump, because for washer, dryer, dishwaher etc. we are dilligent about using off-peak hours.

I've discovered that it is possible to programme the domestic hot water function of the pump so that it uses off-peak hours rather than just on demand 24/7. Might this be a way to save money? Could I do this without adversely affecting the efficiency of room heating function of the pump, provided I left the room heating function on 24/7?

The user manual warns not to control heating by time control, since this can "affect consumption negatively", but for hot water time control it just says "time control hot water can impair hot water production".

Oh yes, and talking about economy, over August, September and October our electric bill (total) worked out about £80 per month. For November to date - including the 21 days we had raised the heat curve to get warm water to the radiators - we have used about £190 worth! OK, some of this will be because of cooler weather, and some because of a modest rise in tariff, but even so!!!

I am now taking daily meter readings.

Any comments?

Cardew

You look like running up a bill of £250 for the mildest November for many years in a highly insulated new build house! That frankly is a cause for concern.

How big is your house?

richardc1983

gterr wrote: »

Another question if I may (especially for Geotherm if he's reading).

We are on Economy 10 tariff but at the moment we are using more peak rate units than off-peak units. I'm sure this is the pump, because for washer, dryer, dishwaher etc. we are dilligent about using off-peak hours.

I've discovered that it is possible to programme the domestic hot water function of the pump so that it uses off-peak hours rather than just on demand 24/7. Might this be a way to save money? Could I do this without adversely affecting the efficiency of room heating function of the pump, provided I left the room heating function on 24/7?

The user manual warns not to control heating by time control, since this can "affect consumption negatively", but for hot water time control it just says "time control hot water can impair hot water production".

Oh yes, and talking about economy, over August, September and October our electric bill (total) worked out about £80 per month. For November to date - including the 21 days we had raised the heat curve to get warm water to the radiators - we have used about £190 worth! OK, some of this will be because of cooler weather, and some because of a modest rise in tariff, but even so!!!

I am now taking daily meter readings.

Any comments?

I would see how you go now when it comes to usage of electricity now you have been able to change the temp sensor.

Does raising the heat curve bring the electrical elements on?

gterr

Cardew: Yes, thankfully, as explained in recent posts, I have now returned the heat curve back down to the factory settings and have sorted out the radiator problem by cutting out the unwanted influence of a room sensor that just happens to be located in the warmest place in the house.

Now my electricity usage has halved. (Very) early indications, based on just a couple of days readings, suggest a monthly bill of £122. Still a hike from £80 but understandable perhaps with the rise in elec prices and the fall in outside temp.

What annoys me is that the decision to adjust the heat curve upwards was not mine, but that of the plumber, following a 30 minute phone call to Worcester-Bosch regarding our radiator problem. Yes, of course, this change DID give us warm (hot actually) water to the rads, but it wasn't the proper solution to our problem - just a quick fix to shut the customer up. Just suppose I'd left it like that until I got my next electricity bill based on actual readings!!

And now, of course, I've discovered that we are using more peak units than off-peak. Unless I can reverse this (perhaps by putting time controls on the hot water production) we'd be better off on a standard tariff.

This house is a 3-bed detached 1.5 storey new build in the Highlands.

We also own a 2-bed detached holiday cottage nearby, built 1980, smaller of course, but with inferior insulation. This is all-electric, heated by a wet CH system powered by an Amptek electric boiler. The average monthly bill is £75.

I realise that we must spend time optimising the ASHP settings for the new house, but so far I'm not overly impressed with either performance or economy.

gterr

richardc1983 wrote: »

Does raising the heat curve bring the electrical elements on?

You mean the auxiliary immersion heater? No, not at the outdoor temperatures we have at present, but it would in the depths of winter. But raising the heat curve raises the flow temperature, and with it the use of electricity. I was surprised by how much, though.

(But then remember that old adage about reducing your thermostat by 1 degree and saving ?? percent of your electricity usage?)

Yes, I will wait and see how things go. I think the crisis is over!