ASHP: lagging pipes in loft

albyota

Gterr, I would have thought the motorised valve supplying the UFH should be controlled / opened when there is a demand from the room stat.

Also, as a note, if the radiators are completely off between programmed times...then, when the programmer brings these rads back on, all this cool water in the radiators is having to flow through the UFH circuits before it gets back to the store, which is giving the heat pump a tremendous amount of work to do, to get the water back up to a decent temperature, I would change the programmer for the radiators to either come on much earlier but turn the TRVs down or leave the rads on constant but at a lower temperature either by the room stat or TRVs.

albyota

Sorry.... I said I wouldn't interfere.

gterr

albyota wrote: »

Sorry.... I said I wouldn't interfere.

The more the merrier!

Your comment on the motorised valve:

I am really unclear on its status. As far as I can tell it's mounted on the flow pipe, and also as far as I know, the rads and the U/F are in series, so, if this valve turned off then the flow to/from both rads and U/F would be stopped, wouldn't it?
Also, I wonder which room stat would trigger this valve. If it's the single room stat linked to the pump then there might be a problem because I've reduced the 'influence' of this stat to zero in the pump controls. Apart from this, each room downstairs has its own timer/stat, and the rads just have TRVs and the single time clock.

lovesgshp

This may be a simpler way to illustrate what I am talking about, as you may be restricting the heat flow. Alboyota may be better to clarify what I mean.
http://www.myson.co.uk/static_files/my/media/downloads/ABV_Technical_instruction.pdf

gterr

albyota wrote: »

Also, as a note, if the radiators are completely off between programmed times...then, when the programmer brings these rads back on, all this cool water in the radiators is having to do, to get the water back up to a decent temperature, I would change the programmer for the radiators to either come on much earlier but turn the TRVs down or leave the rads on flow through the UFH circuits before it gets back to the store, which is giving the heat pump a tremendous amount of work to constant but at a lower temperature either by the room stat or TRVs.

That's a very good point.
I'm just mystified as to why the system wasn't designed so that we have the option of switching off the rads completely without prejudicing the U/F (or the other way round for that matter).

lovesgshp

albyota wrote: »

Sorry.... I said I wouldn't interfere.

No problem, if we can sort this out!!!

gterr

Geotherm wrote: »

This is the type of valve I mean. As soon as the TRV shuts down, the flow is carried on.
http://www.myson.co.uk/products/automatic_bypass_valves.asp

I can't see anything like this anywhere in the loft. The third photo I posted of the arrangement in the loft does show some sort of a valve, but this is on the domestic hot water pipework i think (the pipework that has the expansion vessel on it.)

Shall I try opening all the rads and swtiching the rad rimer to 24h on? (begs the question why do we have this timer if so!)

lovesgshp

gterr wrote: »

I can't see anything like this anywhere in the loft. The third photo I posted of the arrangement in the loft does show some sort of a valve, but this is on the domestic hot water pipework i think (the pipework that has the expansion vessel on it.)

Shall I try opening all the rads and swtiching the rad rimer to 24h on? (begs the question why do we have this timer if so!)

Try the rad timer off, but the rads on the trvs on your settings, just for a night. Take the meter reading tonight before and after in the morning. It may start to show the problem.

gterr

Rad time clock switched to always off, individual rad valves turned half way open? Will do.

I am taking meter readings every 24 hours anyway, so will read tonight and in morning. Out all day tomorrow so will report back tomorrow night.

Thank you ever so much.

TiredGeek

gterr wrote: »

original plumber told us not to turn off all the rads at once otherwise a pump would burn out, so we keep the bathroom one turned on at the rad valve.

Sounds very much like there is no auto bypass valve fitted or he wouldn't have told you this. I would have thought one would have been an absolute necessity if there's TRVs fitted.

Geotherm and Albyota will fix it if anyone can