I thought the pipes going in and out of the ASHP should be insulated

[saveasteading]

3 hours ago, Canski said:

cheaper to do it right the first time. 

Which suggests that they don't carry the right kit, and tjey work day to day with a bit on the way past  from SF, that will fit.

So the whole installation is of concern, especially when they lie, or make an excuse or just don't know much, whichever it is. I'd check their insurance too.

 

What is the betting that they reluctantlypripose to  fit some economy pipe insulation that will be feeble but also fail in the outdoors.

Edited September 23 by saveasteading

[saveasteading]

Aren't these pipes going to be the biggest heat loss of the whole system?

I've always overdone it if anything, and would be very inclined to put a boxing around it even after it is properly wrapped.

We all put 150mm under a new floor slab, over a big area. Why not £20 more expense at this small improvement / easy gain? Payback one week?

[jack]

2 hours ago, scottishjohn said:

NO what i have is exactly true ,even if you run a single zone 

heat from ASHP should not be going anywhere until it gets to the distribution point  and DHW tank

  and who inthier right mind would run a single zone in a 400sqm house 

with 4 bedrooms and other rooms you do not use very day 

 

Not 400 m², but I have a four bedroom, 289 m² house where I've been successfully operating my UFH as a single zone for nearly 10 years. It's a very well-insulated house so there's no heating in the bedrooms.

 

We do have panel heaters in the bathrooms that get used in winter, but that's it for heating upstairs.

I suppose if I had wet UFH in the bathrooms, I'd want to run those on a separate zone(s), but that's about it.

 

As for different rooms requiring different heating outputs, that's just a set-once adjustment using the manual manifold flow controls. I haven't bothered - they're all just wide open.

 

Also, if you know in advance that you want more or less heat in a particular room, you could adjust the pipe-spacing accordingly.

[scottishjohn]

6 hours ago, JamesPa said:

Single zone btw does not mean all rooms have to be at the same temperature

that would depend on your definition of a zone 

my useof the word zone is in relation to room stats and number of manifolds 

EG one manifold  for downstairs ,one for upstairs ,but how ever you describe it pipes from heat source to distibution should be insulated if for nothing else to cut down on heat loss from the pipes to areas not intended to be radomly heated 

[scottishjohn]

4 hours ago, jack said:

 

Not 400 m², but I have a four bedroom, 289 m² house where I've been successfully operating my UFH as a single zone for nearly 10 years. It's a very well-insulated house so there's no heating in the bedrooms.

 

We do have panel heaters in the bathrooms that get used in winter, but that's it for heating upstairs.

I suppose if I had wet UFH in the bathrooms, I'd want to run those on a separate zone(s), but that's about it.

 

As for different rooms requiring different heating outputs, that's just a set-once adjustment using the manual manifold flow controls. I haven't bothered - they're all just wide open.

 

Also, if you know in advance that you want more or less heat in a particular room, you could adjust the pipe-spacing accordingly.

as all my floors are stick down LVT there was no way I would take the chance of needing heating later  upstairs etc .so every room has its own stat  and ufh  

I cannot make any real  valid comment on running yet as I have not had a winter in here yet 

 

[JamesPa]

23 minutes ago, scottishjohn said:

7 hours ago, JamesPa said:

Single zone btw does not mean all rooms have to be at the same temperature

that would depend on your definition of a zone 

my useof the word zone is in relation to room stats and number of manifolds 

EG one manifold  for downstairs ,one for upstairs ,

I would go with essentially the same definition and indeed it was the definition I had in mind when making the assertion. 

 

My understanding is that UFH manifolds generally have flow adjustment valves on each loop so that the flow through each loop can be balanced.  There is nothing to stop you tweaking these (per @jack above) so that the different loops end up at different temperatures, just like you can tweak the LSVs on radiators so that rooms end up at different temperatures (even if you effectively take the TRVs/room stats out of the control loop by setting them above the desired temperature so they act purely as limiters). 

 

That, combined with properly adjusted weather compensation, is the best (ie most cost effective and most comfortable) way, in most cases, to operate as ASHP and in many cases even a boiler.  Of course there are always exceptions such as houses where the external insulation is either poor or not materially better than the insulation between rooms, houses with very low thermal mass, or houses which are of an extreme shape (eg long and thin or physically separated), but most houses aren't like this, they are approximately cubic with reasonably good external insulation and negligible internal insulation.  Unfortunately the controls industry has brainwashed us into largely pointless and often counterproductive micro zoning in both time and space.  The main contribution this has made (other than to their profits) is to create a lazy heating industry that throws in an oversized heat source, whacks it up to max flow temperature, and leaves the controls to 'sort it out' at considerable expense of comfort and cost for the consumer.

 

23 minutes ago, scottishjohn said:

but how ever you describe it pipes from heat source to distibution should be insulated if for nothing else to cut down on heat loss from the pipes to areas not intended to be radomly heated 

Agreed.  That said uninsulated space heating pipes within the insulated envelope don't matter much if at all because they contribute to the emitter area.  Uninsulated DHW pipes matter even within the insulated envelope, because they are hot when you don't want the space heated.  Floor/ceiling voids may or may not be 'within the insulated envelope' depending on construction.

Edited September 23 by JamesPa

[JamesPa]

27 minutes ago, scottishjohn said:

as all my floors are stick down LVT there was no way I would take the chance of needing heating later  upstairs etc .so every room has its own stat  and ufh  

I cannot make any real  valid comment on running yet as I have not had a winter in here yet 

I would probably do the same because its future proof (in the same vein I have TRVs on all my rads), although I might put in the wiring and save on the actual stats.

 

And then I would turn the stats up to 2C above the desired target and balance the loops (in the same vein all but 2 of my 16TRVs are turned up to max and their heads unscrewed so they almost fall off, thus rendering them inactive; the rooms are balanced on the LSVs) 

Edited September 23 by JamesPa

[Gone West]

On 23/09/2025 at 10:41, joth said:

That's definitely a monobloc

What is it that looks different between a monobloc and a split system ASHP.

[-rick-]

Refrigerant lines will be small diameter copper, not large diameter flexible hoses. Fittings are different too.

[JohnMo]

18 minutes ago, Gone West said:

What is it that looks different between a monobloc and a split system ASHP.

Monobloc has the plate heat exchanger between refrigeration gas and water in the outside unit, a split unit has the heat exchanger in the house 

[Gone West]

3 hours ago, JohnMo said:

Monobloc has the plate heat exchanger between refrigeration gas and water in the outside unit, a split unit has the heat exchanger in the house 

Yes I am aware of that but @joth said "it's definitely a monobloc" just from the picture of the back of the unit, so I was wondering what the back of a split unit looks like, that is so different from a monobloc. It looks like @-rick- has provided the answer.

[SimonD]

On 23/09/2025 at 10:41, joth said:

That's definitely a monobloc and those are definitely water pipes.

 

Insulation is required by part L and by MCS MIS 3005, which I presume is why city plumbing think it's OK to charge over 200 notes for a pair of flexis 

https://www.cityplumbing.co.uk/p/pump-house-ashp-flexible-hose-750mm-female-114in-fh-750-2-114-f/p/648052

 

EDIT F*** me! I think that's the price for a single flexi, so > £400 for the pair. I'm in the wrong business.

 

 

Yup, that's City Plumbing if you don't have an account and a friendly person at the counter. Try these instead. Still a lot of money mind you. And then 

 

https://www.bes.co.uk/flexible-hose-1-bsp-f-swivel-x-28mm-x-500mm-pair-25287/

 

https://www.bes.co.uk/inta-pre-insul-heat-pump-hoses-1-bsp-f-swivel-elbow-x-28mm-comp-x-750mm-pair-26190/

 

On 22/09/2025 at 15:47, CalvinHobbes said:

pipes going in and out of the ASHP should be insulated

 

As above, there's just no excuse not to. Unless the system is filled with glycol, I'd also want to see anti-freeze valves on there.

[CalvinHobbes]

Husband thinks he said there was refrigerant....we will check. Thank you all so much.

[JohnMo]

1 hour ago, SimonD said:

Try these instead.

 

You guys need to shop about more 

 

https://coolenergyshop.com/products/1-500mm-flexi-hose-individual?_pos=5&_psq=fle&_ss=e&_v=1.0

 

[JohnMo]

1 hour ago, SimonD said:

there's just no excuse not to. Unless the system is filled with glycol, I'd also want to see anti-freeze valves on there

You really need the insulation for heat conservation. Why do you need glycol or anti freeze valves.

 

Glycol kills circulation pump performance and needs a slight high flow temp. Antifreeze valves just spill water, need a very long power cut and super low temperature, for them to save anything.

[HughF]

1 hour ago, CalvinHobbes said:

Husband thinks he said there was refrigerant....we will check. Thank you all so much.

Sorry, what do you mean by this post? 
 

You have a monobloc unit, there shouldn’t be anything related to refrigerant to worry about.

[sharpener]

On 24/09/2025 at 13:15, -rick- said:

Refrigerant lines will be small diameter copper, not large diameter flexible hoses. Fittings are different too.

 

Arent't they normally different diameters as the liquid refrigerant is much denser than the vapour returning to the compressor? Don't know for sure as I haven't got one.

[-rick-]

5 minutes ago, sharpener said:

Arent't they normally different diameters as the liquid refrigerant is much denser than the vapour returning to the compressor? Don't know for sure as I haven't got one.

 

That sounds right (don't have one myself). A quick google reveals this link that suggests one line is 1/4" and the other 3/8" for a 12k BTU system. So both lines are still much smaller than the 22/28mm+ pipes we see on monoblocs here.

 

https://forum.heatinghelp.com/discussion/165244/lg-line-set-size