Air Source Heat Pumps

zeupater

gterr wrote: »

Don't know. I will try this out. Thanks for the idea.

Do you think this mixing valve set at 50C has any bearing on the problem?

Hi

I'm not a heating engineer, just trying to work though it logically .... my guess is that with the mixing valve being set at 50C it will never mix as your feed temperature will never reach this on the U/F circuit (unless the circuit also feeds the H/W cylinder) .... a pure guess is that your system needs to be balanced so that some of the flow goes through the radiators even when the U/F circuit is calling for heat .... hence the test of turning the U/F circuit off with the thermostat ....

HTH
Z

lovesgshp

Having read the problems you are experiencing gterr, then I think they are related to the heat curve settings to your buffer tank.
With a installation here a couple of years ago, the curves were adjusted to be equal for all the range of external temps. (UFH x 2 temp zones, upper and lower floors + heated towel rails ).
As your pump is a IVT Air (rebranded WB), I posted quotes of your problems to one of our engineers to see what he thought, but he could not give a definitive answer.

There is much confusion on this post.
It's impossible to understand what is the real problem. It would be necessary at least a diagram of the plumbing connections. With IVT Air there are many and many connection options.
Errors can be taken in the type of connection or just in the control systems management. The user must turn to those who have designed/installed the system. If they can't help him, the first error was the choice of supplier.
Even the best product may not be satisfactory.

Well, it is very difficult to solve these problems in a blog. It should be analyzed from the beginning the whole project.

Sorry that I cannot be more helpful, as we have installed IVT products for over 10 years now. You do need to get WB out to resolve it though and would have been better if you had been there for the commissioning, so you had more insight into the Rego unit.

gterr

Yes, thanks to everyone for the helpful posts. Will click your 'thanks' buttons shortly.

I'll get back with answers to some specific questions in 48 hours or so when the system has had a chance to settle to the new settings.

And, yes, it would be good to get Worcester back out to advise us on our installation.

richardc1983

gterr wrote: »

Thanks jeepjunkie.
Setting the heat curve as recommended for U/F plus rads, the flow temp will only reach 50 C if the outside temp drops to -24 C.

Even with the higher heat curve settings (the ones that currently allow my rads to stay warm) the flow temp would only reach 50 C with an outside temp of -13C. We are in the Highlands but on the coast. The lowest temp we got during the last 2 'bad' winters was -11 C on one occasion.


I have adjusted heat curve back to maunfacturer's recommended settings (V=20, H=55), and have turned the influence of the internal heat sensor down to 0 (off). I'll give it 48 hours and report back here what happens re my radiators.

Thanks for all the helpful ideas.

Confused why u have turned the internal thermostat to 0. Surely that keeps the system off? I wouldhave thought turning it to max would be better as in theory it wil never reach 30c. Perhaps someone else can back this up I have just woken up and on nights.

lovesgshp

richardc1983 wrote: »

Confused why u have turned the internal thermostat to 0. Surely that keeps the system off? I wouldhave thought turning it to max would be better as in theory it wil never reach 30c. Perhaps someone else can back this up I have just woken up and on nights.

The internal sensor is only on a influence level against the outside air temp. The 2 basically talk to each other. If you turn it to 10 max, then it overides the outside unit, but can result in higher running costs. Normal setting would be around 5 - 7.
Room setting temp is also within the pump, but if the user has thermostats, then this sensor would not normally be required.

zeupater

richardc1983 wrote: »

Confused why u have turned the internal thermostat to 0. Surely that keeps the system off? I wouldhave thought turning it to max would be better as in theory it wil never reach 30c. Perhaps someone else can back this up I have just woken up and on nights.

Hi

It seems that the radiators are on a separate timed circuit to the U/F so the idea would be to effectively cut the demand from the U/F and see whether the radiators do warm at all ..... I doubt that it would take more than a couple of hours to check this out though ....

The odd thing is that the radiators are reported to only warm to 'tepid' on an intermittent basis ... my initial thought is that this could be when the U/F thermostat cuts out and the U/F circulation stops, which allows the heat to flow to the radiators ..... if this is the case then surely it would be a case of somehow balancing the flow between the different circuits

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 ...

I'm just really posing questions but hopefully they make sense ....

HTH
Z

lovesgshp

Gterr
Are there any alarms recorded on the pump menu?

gterr

OK guys - good news I think.

At 4.30pm. All U/F zones are at their selected temperatures and all U/F flow meters at zero (coils closed).

Husband has finished showering and control panel confirms hot water has been reheated back to target value (pump gives priority to domestic hot water over heating water so needed to get this out of the equation). Heat curve is set to manufacturer's recommended setting for efficiency and economy.

According to control panel: Room temperature (sensor in hallway) 22 C.; Outside temp 10 C; hot water temp 51 C; flow temp 33 C.

and...... Rad temperature in upstairs study approx 25 C and steady!!

I am well pleased with this. Perhaps a bit early to say, but looks as though it was the room temperature sensor influence on the flow temp that was causing problems. Now that this 'influence' is switched off, the flow temp depends on outside temp only, and all zones rely on their own timer/stats to achieve correct temperature.

I will see what happens when the U/F coils open.

Many thanks for the help so far. I may come back for more!

Cardew

gterr wrote: »

and...... Rad temperature in upstairs study approx 25 C and steady!!

25C in a radiator is very low - will that keep the room warm even at 10C outside?

gterr

Cardew: Seemingly yes. Temperature in room has risen from 18C to 20C no bother and TRV has now switched radiator off. (Have checked can get it warm again if I turn up TRV to max.) The rads are oversized, of course, compared to the rads you would have for other types of heating, and level of insulation is high. I have thermometers everywhere at the moment because I can't trust my own assessment of what is a comfy temperature. Bathroom is toasty!

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.