ASHP: lagging pipes in loft

gterr

Hi there,

We have an ASHP - Worcester Bosch Greensource, with internal hot water distribution unit. We've been struggling with unimpressive performance and cost, and I think I may have discovered why.

We are in a new build, and I have just been up in the loft for the first time. Many of the slabs of insulation that are supposed to be slotted between the rafters/roof trusses in the roof itself have slipped or have simply fallen out and are lying on the loft floor. Also, there is about 15 m of pipework including the flow and return from the internal hot water distribution unit part of the heat pump (which is installed in the downstairs utility room), and the flow and return from the primary store tank to the heating pipes (a mixture of U/F heating and radiators) completely naked! The only pipes that are lagged are the long runs of hot and cold supply pipes for the domestic hot water. In one corner under the eaves there's a stash of pipe insulation which looks to be a superior grade to the normal 22mm stuff you get from plumbing merchants.

Just before I refix the slab insulation to the rafters and then set about lagging all the heating pipes: I am not being crazy, am I? There isn't some strange new logic somewhere that says pipework from heat pumps doesn't need to be lagged in the lofts of new builds?

Thanks for your time.

bernithebiker

gterr wrote: »

Just before I refix the slab insulation to the rafters and then set about lagging all the heating pipes: I am not being crazy, am I? There isn't some strange new logic somewhere that says pipework from heat pumps doesn't need to be lagged in the lofts of new builds?

Thanks for your time.

Not as far as I know!

Both flow out and return will be warm/hot, so will lose heat in a cold environment, and you have a long run.

So yes, lag them as best you can, although I wouldn't expect it to transform the performance of your machine.....

lovesgshp

Insulate as many of the heating supply/return pipes as possible. It is no good cooling the heat down in the loft.

albyota

If this is a new build, I'd be going back to the builder / developer / heating company, to get this put right, and depending on how long you have been in the house, some compensation for the extra electricity you have used trying to heat the loft. Keep us posted on the performance of the WB ASHP.

gterr

albyota wrote: »

If this is a new build, I'd be going back to the builder / developer / heating company, to get this put right, and depending on how long you have been in the house, some compensation for the extra electricity you have used trying to heat the loft. Keep us posted on the performance of the WB ASHP.

Thanks. Yes, I may well do that. We've been in here for over a year. Part of the problem was that the original plumber was sacked by the main contractor half way through the job. A new plumber was brought in to finish off. We've had no end of frustration with the pump because the replacement plumber has no experience of the Worcester pumps and didn't design the installation we have.

Have now insulated pipes in the loft, and inspected elsewhere. The external pump unit has two flexible hose connectors, approx 22mm, perhaps a bit wider. These are covered in a cloth-like material. (Hard for me to describe these as a non-plumber, but the material looks a bit like the stuff that used to cover iron flexes.) Are these insulated already, or do they need something over the top of the material? The other external pipes seem to be well insulated already.

Another question: Up in the loft I've been trying to identify pipework. We have U/F heating downstairs, and radiators upstairs. Unless I'm mistaken it looks as though we have only one heating circuit, i.e. heating water flows round the radiator circuit and _then_ flows downstairs to the U/F heating manifold (where there is a mixing valve) then returns to the primary hot water store in the loft, and then back downstairs to the pump. Is this usual? I would have expected two separate circuits. My precious heating water is having to travel an almighty long way if so! Maybe there is some other pipe arrangement I can't see, so I could be wrong about this, but it is certainly the case that the flow pipe that runs from the secondary store in the loft to the U/F manifold gets hot when the radiators are demanding heat and the U/F heating is not.

I have taken a meter reading and will see if economy and performance improves. I am on a Scottish island and the outside temp is 3 C just now (7pm) and falling.

Thanks for your time.

lovesgshp

Gterr.
Can you provide some pictures of the setup. The worcester bosch unit is a IVT Swedish heat pump, so the supplier should also have given all connection details to the plumber.

gterr

Geotherm wrote: »

Gterr.
Can you provide some pictures of the setup. The worcester bosch unit is a IVT Swedish heat pump, so the supplier should also have given all connection details to the plumber.

Yes, certainly. Tomorrow. Thanks for your time.

gterr

Geotherm wrote: »

Gterr.
Can you provide some pictures of the setup. The worcester bosch unit is a IVT Swedish heat pump, so the supplier should also have given all connection details to the plumber.

OK here goes (never posted photos before)

Key:
A is labelled "outdoor heat pump" and is flow from outdoor heat pump to internal unit (hot water distrib unit, HWDU).
B is labelled "return heating" but seems to be the return from primary store to HDWU.
C is labelled "flow heating" but is the flow from HDWU to primary store
Z is labelled "return outdoor heat pump" and I think is the return from HDWU to outdoor unit.
E is also labelled "flow heating" but is probably flow from primary store to heating circuit.
D is also labelled "return heating" and I think is the return from heating circuit to primary store.
F is expansion vessel for domestic hot water.
G is the flow to the U/F manifold (the other end of E, presumably)
H is mixing valve set to 50 C
J is a single elctrical isolation switch for both rads and U/F
K is a time clock for just the rads (rads have TRVs)
L is outdoor flexible connectors. Should these have more lagging?






(In the photo above the D bottom left should be Z. Sorry)











Ans lastly, my sketch of what I assume our installation is:



Please excuse any stupidity.

Very many thanks for your time.

TiredGeek

Those outdoor pipes are not insulated - that's the flexible pipes supporting braid you're seeing.
You'll want some good quality stuff for them, Armaflex for instance is a good choice as it's very flexible, and the thickest wall you can find.
Try a small piece of 22mm insulation (you must have a bit laying about) and see if it fits, if not then 28mm insulation will.

The rest is beyond me as I don't know that type of unit so I'll leave it to the experts

gterr

TiredGeek wrote: »

Those outdoor pipes are not insulated - that's the flexible pipes supporting braid you're seeing.
You'll want some good quality stuff for them, Armaflex for instance is a good choice as it's very flexible, and the thickest wall you can find.
Try a small piece of 22mm insulation (you must have a bit laying about) and see if it fits, if not then 28mm insulation will.

The rest is beyond me as I don't know that type of unit so I'll leave it to the experts

Thanks. Will get something on to those pipes tomorrow and order some Armaflex.

We have used 65 units electricity today. There are only 2 of us in this small house. We haven't used the washing machine or drier, just the dishwasher once, and needed to light the woodburner to boost the temp in the lounge this evening (U/F heating could not get it up to 21 C). It's 2 C outside just now (23.15) I hope tomorrow's pipe lagging will make some difference. Can't go on with this level of electricity usage. We're not even cosy!

lovesgshp

Hi Gterr.
Get the flow and return pipes outside insulated as much as possible as TiredGeek says. The black pipes, that you show in the picture, the one with the white connection on the external unit, is just power supply. The other one I cannot identify. as does not appear on the installer manual., can you trace where it goes??

Armaflex type O is recommended for the outside pipes