Mixer valve on 100% UFH install?

[Myatix]

@NickfromwalesI just downloaded the pump installation manual from Grundfos and I am sorry but what you are saying about the pump is incorrect.

 

As you can see from the screen shots above.

[Nickfromwales]

1 hour ago, Myatix said:

@NickfromwalesI just downloaded the pump installation manual from Grundfos and I am sorry but what you are saying about the pump is incorrect.

 

As you can see from the screen shots above.

When I was called out to a job where 3 of these identical pumps were installed I contacted Grundfos as all 3 had seized impellers. This was a bit over a year ago. When I was sent a pdf for the recommended installation positions it was defo showing not fitting them ‘upside down’. The reason was that air bubbles would constantly be pulled downwards into the pump body but would try to rise to escape, thus causing issues with pump longevity. 
In 3 decades of heating and hot water installation I have only ever seen 4 pumps fitted this way. All 4 were kaput. 
Other pumps I’ve installed ( in what is an industry recognised orientation ) ‘the right way up’ have been in in some installs for coming up to 20 years.

I can’t pull up the info, and cannot argue with the literature you’ve posted, but no plumbers I’ve ever worked with / for would accept a circulation pump installed this way.

The way your setup is installed does not promote self purging of air, and is not as the manufacturer of the manifold recommends you install it. Instead it promotes air being drawn down into the loops where it will eventually sit and cause air locks. I concede to your posted info and confidence in this being fine.

 

[Myatix]

7 hours ago, Nickfromwales said:

When I was called out to a job where 3 of these identical pumps were installed I contacted Grundfos as all 3 had seized impellers. This was a bit over a year ago. When I was sent a pdf for the recommended installation positions it was defo showing not fitting them ‘upside down’. The reason was that air bubbles would constantly be pulled downwards into the pump body but would try to rise to escape, thus causing issues with pump longevity. 
In 3 decades of heating and hot water installation I have only ever seen 4 pumps fitted this way. All 4 were kaput. 
Other pumps I’ve installed ( in what is an industry recognised orientation ) ‘the right way up’ have been in in some installs for coming up to 20 years.

I can’t pull up the info, and cannot argue with the literature you’ve posted, but no plumbers I’ve ever worked with / for would accept a circulation pump installed this way.

The way your setup is installed does not promote self purging of air, and is not as the manufacturer of the manifold recommends you install it. Instead it promotes air being drawn down into the loops where it will eventually sit and cause air locks. I concede to your posted info and confidence in this being fine.

 

@NickfromwalesI understand what you are saying but in a closed heating system there is very limited air in the system if the installation has been done well. It’s a closed system, also you can’t see the rest of the installation from the images I have provided. There are numerous automatic bleeding valves in the system and in the boiler which are all above the manifold and will naturally bleed any air, if any out of the system.

But thanks for your input! I am happy to go with the manufacturers recommendation.

Edited November 3, 2022 by Myatix