My Install - some questions!

[JohnMo]

6 minutes ago, Duncan62 said:

 

Thinking about it, should the Freezer valves be sited at the lowest point before the heat pump, or will anywhere outside do it?

Low points - outside, if that at the heat pump, that's where they go.

[Nickfromwales]

5 hours ago, Duncan62 said:

 

Thinking about it, should the Freezer valves be sited at the lowest point before the heat pump, or will anywhere outside do it?

Here’s the last one I installed. 
 

 

Lagging was finished after leak testing. 

[Duncan62]

Thank you so much.

I've got outdoor lagging and will do as you do!

[JohnMo]

This is what it looks like lagged 

[Duncan62]

Thank you all, uninsulated until I get it up and running in case of any leaks, but system installed and closed loop. 

 

Next challenge is flushing the UFH loops (only 3x100m) and filling the system from the now connected fill hose under the expansion vessel.

 

Also need to add the biocide and anti-corrosion. Wish me luck.

[Nickfromwales]

27 minutes ago, Duncan62 said:

Thank you all, uninsulated until I get it up and running in case of any leaks, but system installed and closed loop. 

 

Next challenge is flushing the UFH loops (only 3x100m) and filling the system from the now connected fill hose under the expansion vessel.

 

Also need to add the biocide and anti-corrosion. Wish me luck.

 

 

Have you checked if there's an automatic air vent inside the heatpump that needs opening? Some come open, but I've found some which are loose but not 'open'.

 

Also, any reason why you have an inline trap after the P of the washing machine trap? No need for the inline (waterless) one afaic.

[Duncan62]

5 hours ago, Nickfromwales said:

 

 

Have you checked if there's an automatic air vent inside the heatpump that needs opening? Some come open, but I've found some which are loose but not 'open'.

 

Also, any reason why you have an inline trap after the P of the washing machine trap? No need for the inline (waterless) one afaic.

I'll check the heat pump thank you.

 

Airless trap because I had already bought it but for airtightness test it's useless for the pressurisation test as it blows straight open, so added a u bend too.

[Duncan62]

So, filled with water. Lots of leaks....

Which was unexpected. Going round tightening everything again.

[JohnMo]

2 minutes ago, Duncan62 said:

So, filled with water. Lots of leaks....

Which was unexpected. Going round tightening everything again.

Don't overtighten fitting with olives.

[Duncan62]

31 minutes ago, JohnMo said:

Don't overtighten fitting with olives.

 

I think this may be my issue, I knew not to offer tighten, so maybe didn't do it enough. 

 

I only have normal spanners so don't think I could have overtightened as wasn't forcing anything...

 

I'll open one up and look at the pipe, hopefully it doesn't look like a fat finger on a ring!

 

Been advised to add some paste to the olives before tightening to help with the leaks.

[Bancroft]

On 10/02/2026 at 22:39, JohnMo said:

Best ratio - is no glycol at all - why are you adding. It just degrades system performance.

I put this question to a UFH guy as it said glycol was needed.

 

He said that they recommend glycol only for the initial fill while the property is being built.  This is in case there is a prolonged cold spell before the system has been comissioned.

 

He then said that once the system is ready for commissioning, the glycol should be drained out and water put in.

 

Would be nice if they actually explained that in their information.

[SimonD]

6 hours ago, Duncan62 said:

Been advised to add some paste to the olives before tightening to help with the leaks.

 

Yes, absolutely. It doesn't just help with leaks, it helps lubricate the olive and nut so it's much easier to tighten it up without horrible squeeks and judder. On larger diameter compressions, you can use a bit of the paste on the thread which helps a lot too.

 

The other thing you're going to be swearing about is the use of primary pro insulation. God awful stuff and the sealant is a messy nightmare - you also have to mend the outer protective layer on regular occasion. I only use Armaflex or Kaiflex with the adhesive and tape. TBH I now use trunking wherever possible now.

 

Also, your anti-freeze valves shouldn't be installed on top of each other, but about 150mm apart. But what you can do with your situation is get the half bend covers like these: https://www.bes.co.uk/inta-zeroguard-anti-freeze-valve-protector-26812/ so if the top valve dumps its contents, it doesn't pour it all over the one below. An alternative in some instances is to have 1 anti-freeze valve at the lowest point of the pipework.

 

And lastly, to be picky, you've got a lot of weight hanging of the connectors on the heat pump, no pipe clips until the pipe goes through the wall and this is what's holding the weight of the pipes. Personally, I would have run the flexis straight from the heatpump and then have the isolation valves on hard pipe properly clipped to the wall for support.