UFH Mixing Valve advice on Air Source Heat Pump set up

[Marvin]

Hi @MorganP

 

This is a classic: Never have the cable going in at the top of the pump! The 4 Allan key bolts allow the motor housing to be rotated to any of the 4 sides and best if the cable inlet is at the bottom,  BUT ONLY with the system drained or the pump isolated.

 

I haven't read all the info here... Have you bled the pump? 

 

[John Carroll]

30 minutes ago, MorganP said:

 

 

My best guess is 12mm and 15mm - there are two different sizes. There are photos in this earlier post:

 

16mm piping will require a ~ pump head of 2.5M at 3.0LPM & 90M of pipe, 12mm will require ~ 11M pump head so with this 6M pump around 2.0LPM max through this piping but 3.0LPM through any of the 16mm loops should be quite possible with this pump,  can you measure  the diameter of the loops, or at least find one 16mm & one 12MM, you can measure them where they join the manifolds.

 

 

Edited yesterday at 09:16 by John Carroll

[Nickfromwales]

21 minutes ago, Marvin said:

This is a classic: Never have the cable going in at the top of the pump! The 4 Allan key bolts allow the motor housing to be rotated to any of the 4 sides and best if the cable inlet is at the bottom,  BUT ONLY with the system drained or the pump isolated.

Not exactly life or death tbf? And it’s not caused an issue to date…

 

It’s upside down, pumping the water down instead of up, which gripes me as much as that cable gripes you, however the effects of having the pump ‘the wrong way around’ are more consequential, air wants to sit in the pump, when low flow rates cannot purge the air downwards when fighting over it wanting to rise upwards.

 

The air does rise and settle when the pump is off, but sits there without an automatic air vent to let it out, which is why I always bin the manual vents and fit 3rd party AAV’s eg so these do a bit of self maintenance/bleeding.

 

21 minutes ago, Marvin said:

Have you bled the pump?

Doubt bleeding the pump is an issue, more the fact it is in a constant battle trying to pull any trapped air downwards, through, and out; it can then only be released by being pushed through the loops to get back to the highest part of the manifold, where the whole damn cycle started again!  
 

Get some AAV’s fitted asap here plz!!

 

 

@MorganP

3 lpm flow rate on the 12mm pipe is not too shabby tbh, and if the pump was zooted you’d not even have that. How old is the pump? Is it noisy?

 

We need air vents fitted as the first steps in the process of elimination, before changing anything more (imo). 

[MorganP]

14 minutes ago, Nickfromwales said:

Get some AAV’s fitted asap here plz!!

 

 

@MorganP

3 lpm flow rate on the 12mm pipe is not too shabby tbh, and if the pump was zooted you’d not even have that. How old is the pump? Is it noisy?

 

We need air vents fitted as the first steps in the process of elimination, before changing anything more (imo). 

 

Re. AAVs - does the system need to be drained first? And can any heating engineer do it? I'm near Newark, Notts and failing to get a good, local UFH engineer.

 

Re. this:

"3 lpm flow rate on the 12mm pipe is not too shabby tbh, and if the pump was zooted you’d not even have that. How old is the pump? Is it noisy?"

 

I'm trying to get 3 lpm but failing! Two are slightly over 2 lpm but the rest are 2 or under. The pump is likely as old as the system - circa 2004. It's not noisy. Would it be worth changing at the same time as fitting the AAVs?

 

[Nickfromwales]

52 minutes ago, MorganP said:

 

Re. AAVs - does the system need to be drained first? And can any heating engineer do it? I'm near Newark, Notts and failing to get a good, local UFH engineer.

 

Re. this:

"3 lpm flow rate on the 12mm pipe is not too shabby tbh, and if the pump was zooted you’d not even have that. How old is the pump? Is it noisy?"

 

I'm trying to get 3 lpm but failing! Two are slightly over 2 lpm but the rest are 2 or under. The pump is likely as old as the system - circa 2004. It's not noisy. Would it be worth changing at the same time as fitting the AAVs?

 

A 20 year old pump has certainly served you well, so I’d defo say it’s time for you to treat your heating setup to a heart transplant! This would also be the next item in the process of elimination anyways, so if you’re summoning a plumber to site then you may as well max out on the value of that visit.

 

So yes, get the pump and the AAV’s done in one hit. Should be max 2 hrs physical work, and prob another hour on site firing it back up and demonstrating / commissions the system before they depart.

 

Re a good fitter near you, that’s simply down to legwork, so get the legs moving . You’re over 5 hrs from me, so I’d be crazy expensive if I called out, so get on the phone and keep ringing around, but if you keep drawing a blank PM me and I’ll see if I know someone nearer you.

 

When you / they drain down, you need to be sure they don’t introduce air into the loops, so don’t choose a nugget or you may inherit issues from their ineptness.

[MorganP]

8 minutes ago, Nickfromwales said:

So yes, get the pump and the AAV’s done in one hit. Should be max 2 hrs physical work, and prob another hour on site firing it back up and demonstrating / commissions the system before they depart.

 

This is invaluable, thank you @Nickfromwales - there is a beer and a giant Toblerone waiting for you all if we should ever meet 👍

 

I do have one last question if I may. Would it be worth getting the whole setup repiped with a new manifold? Something like this which already has the pump and AAV included >> 

It also has a better looking mixing valve set up (mine is dropping 5+ degrees even when fully opened).

[Nickfromwales]

1 minute ago, MorganP said:

 

This is invaluable, thank you @Nickfromwales - there is a beer and a giant Toblerone waiting for you all if we should ever meet 👍

 

I do have one last question if I may. Would it be worth getting the whole setup repiped with a new manifold? Something like this which already has the pump and AAV included >> 

It also has a better looking mixing valve set up (mine is dropping 5+ degrees even when fully opened).

Beer and Toblerone is my Xmas staple tbh. “Get out of my head!! 👉”. lol. 
 

If this has worked for 20 years do you really want to spend on a full overhaul?

 

I would never fit an arrangement where the manufacturer has the pump pumping downhill, instant “no” for me. Most pump manufacturers will show this in the installation instructions with a big ❌.

 

I fit the Ivar setups from underfloor heating parts.

 

Entirely up to you, but these are far superior and have never given me a moments trouble, and the TRV head and capillary feed thermostatic blending valve is way better (smoother) than the standard TMV’s afaic.

 

Your call.