ASHP/UFH install issues and questions

[markharro]

We have our installer here and about half way through the instal. 

 

In the first place I wonder if anyone could help me with any basic things I should be asking the installer so I know the heat pump is configured optimally?

 

The second thing is that they have tested it now. We only have one plumbing run being a cold tap at the sink that is currently working. For some reason water from this was coming through warm. Why could this be?

 

Will probably have a few more things to ask but these are the most pressing. thanks.

[sharpener]

He should (under MCS guidelines)

 

• Set it up with Weather Compensation working
• Show you how to increase/decrease the heating curve in light of experience
• Agree a suitable setback temp and timing for your lifestyle
• Set DHW heating to a sensible schedule (at night if you are on a ToU tariff) not 24/7
• Explain the user interface to you including all controls and indicators
• Give you a handover pack

[markharro]

Thanks @sharpener I wonder if you could also have a look at the pipe runs on the photo I attach. The installer told me that it needs to be doubled back like this to allow easy maintenance into the future. My understanding is that it is best to minimise the outdoor pipe runs and was disappointed to see this. 

[sharpener]

Not seen anything quite like this, but it doesn't look too unreasonable and have seen pix of a lot worse, it is perhaps his usual way so I would let it pass. Am I right in assuming they are flexi connections under the different shiny insulation? This at least puts them behind the HP itself which looks neater. The fittings also need to be insulated as well unless they are the antifreeze valves, and all the joints taped to prevent water ingress.

 

I would get him to fault find fundamental probs like the hw to the cold tap, and simply try and make a snagging list of this minor kind of thing rather than keep pointing things out as he goes along.

 

To add to previous list I would include

• Sort out BUS paperwork if applicable
• Register the warranty with the HP mfr inside their time limit for this

[JamesPa]

4 hours ago, markharro said:

understanding

The pipes connected to the ashp itself should be flexible to stop transmission of vibration.

 

If they are (I can't tell - might be worth checking) then his arrangement keeps the joints to the fixed pipework behind the ashp.  That's a good visual decision.

[Peter M]

That type of sloppy pipework would really bug me, I can be very fussy with pipe runs particularly runs that are outside and visible, even behind units such as ASHP equipment, one installer that I was considering had wanted to run the pipework vertically up behind the ASHP and then drilled through the cavity walls of the garage at high level to run inside the eaves of the attic truss roof rather than kept at low level and 90% out of sight and continued to be run horizontally 250mm above the garage floor and behind what will be my racking and work benches, another didn't even want to give me a schematic or drawing of the install showing the pipe and electrical cable runs.

 

If I'm right every metre of extra pipe run will have an effect of affecting the performance of the ASHP, but I stand to be corrected on this if I'm wrong.

[markharro]

Thanks again @sharpener and @Peter M I have attached some more photos of the way the pipes have been insulated. Even to my fairly untrained eye I am not impressed with it. There are splits and while some joints appear to be glued its not done very well. Also the tape used in some placing in clearly no good - maybe not surprising as the plumber had left and the electrician ended up doing those bits. I am pretty sure I would have done a far better job myself and it would be good to hear what people think? Its costing a small fortune for this ASHP instal (although I will get some money back form the grant when it is done) so I think I have a right to expect an exemplary job.

[Mr Punter]

I think this looks fine.  I would be happy if my plumbers worked to that standard.  What do you think is the actual issue?

[markharro]

I'm mainly going on what someone said above about taping all the joins to make sure no rain can enter. There are lots of areas where that can happen. 

[sharpener]

6 minutes ago, Mr Punter said:

I think this looks fine.  I would be happy if my plumbers worked to that standard.  What do you think is the actual issue?

 

Well for a start there are splits and gaps in several places, if water can penetrate it the insulation properties will be compromised.

 

And although my install hasn't yet been done so I have nothing to compare with first hand it looks like ordinary indoor insulation to me, should be done with something like Primary Pro, maybe someone else will comment on that aspect. Even the old rubber Armaflex was better bc of its smooth outer surface. (My installer is proposing insulated pipe inside black PVC trunking.)

 

What was the resolution to the warm water coming out of the cold tap?

 

 

Edited May 16 by sharpener

[Mr Punter]

If this stuff is that sensitive to a bit of rain it should be indoors or in an enclosure.

[Peter M]

To be fair to the electrician that supposedly finished off the lagging it can be a bit fiddly to get it right and look good, insulation works best when it's tightly fitted without any gaps for water to seep in and possibly freeze in the middle of winter, cutting around drain-cocks and valves once again ain't easy but not impossible by a skilled installer, from what I've seen the black tape is doing quite a lot of the heavy lifting on this 'install'

[Peter M]

Also is that even the correct insulation for outside as some types of lagging can degrade very quickly in strong sunlight which I discovered the hard way.

[Dillsue]

Insulation looks like indoor wall thickness to me. The OD of standard outdoor stuff is way thicker than a compression fitting so It looks to me like it's thin indoor stuff they have used. For heated pipework that's going to spend many weeks of the year in single fugure air temps you need thick walls, no open joints and all fittings covered. 

[markharro]

Thanks @Dillsue I wouldnt know what the correct thickness should be so have attached photos to show what has been used. I think the insulation is the proper outdoor stuff to the best of my knowledge....my concerns are the gaps and length of pipe run

[Dillsue]

Without knowing pipe diameter it's hard to comment on the insulation but personally I'd be wanting 25/32mm wall thickness to minimise heat loss and maximise frost protection. If you use 32mm wall thickness some of the insulation can be cut out of the inside to allow the insulation to fit over the nuts on compression fittings so you have some insulation over everything.

 

Ideally the majority of insulation is unsplit so it gets slipped over the end of the pipework and there's way less gaps to worry about. Formed long radius bends allow the likes of Armaflex insulation to fit neatly over the bends without joins, and reduce flow resistance as a bonus. 

[Andehh]

I wrapped the whole length of ours with quality duct tape on a dry day. Added a few layers for good measure. Only takes 20mins and seals it up tight.

 

Year later still looks fine. Might wrap it in another layer if it looks ropey one day.

Edited May 20 by Andehh

[Andehh]

Still tidying up to do in site....

[markharro]

Thanks. I think the flow and return pipes are 28mm - is there not a standard size? Also is there not a recognised standard thickness for the outdoor insulation? If not how can you know if what the installer has fitted is thick enough?

 

I think taping is a good idea but why should I have to do this on at £13k instal?

 

 

[JohnMo]

14 minutes ago, markharro said:

Also is there not a recognised standard thickness for the outdoor insulation?

Most of what you buy is 19mm for outdoors, although some of mine is 25mm.

 

When flowing a 6kW ASHP will be flowing around 1m3/hr, you can pro rata that figure for different sizes of heat pump.  At that flow rate the fluid velocity is moving through the pipe (28mm) at about 0.5m/s, so the exposure time to the outside world is very limited. So a 10m run of pipe the water is only exposed for 20 seconds.

[crispy_wafer]

For what it’s worth my pipework follows a similar path to yours in that it runs behind then along the wall.

 

I used this stuff on what I’ve done so far (Still WIP)

https://www.bes.co.uk/pre-slit-pipe-insulation-22mm-dia-x-2m-long-25283/

the sticky in the slit is a bit crap, so I painted contact adhesive along it.  It’s not coming apart any time soon.

 

my corners are a bit on the ropey side but I had a roll of uv pipe wrap tape, to cover my sins.

 

 

[Andehh]

The other question, is what have you all done for the drainage? Do you just let it drain into the slab below?

[crispy_wafer]

4 minutes ago, Andehh said:

The other question, is what have you all done for the drainage? Do you just let it drain into the slab below?

When I put the drains in I ran a bit of 110 to the back of the concrete slab.