Suitable Pump Replacement

[Berksguy]

My existing pump is on the way out. It's a Grundfos ALPHA 15-60 130 and about 16 years old. If I use the Grundfos replacement guide it comes out with an ALPHA2 15-60 130 as a suitable replacement. My system is quite large (22 radiators) and I have found, even after balancing, that the radiator furthest away from the airing cupboard struggles to get very warm. Is it worthwhile upgrading the pump to a light commercial one or stick with the suggested ALPHA2?

Thanks for looking,

Steve

 

[ShaunCorbs]

is your system sealed or open vented?

 

[Berksguy]

is your system sealed or open vented?

It's sealed.

 

[ShaunCorbs]

Would stick an 25-80 if you can adjust the pipework

 

[king of pipes]

Dab Evosta 40-70 would be a good affordable replacment these pump can be fitted to most domestic systems with switchable head settings. Kop

 

[Berksguy]

Thanks for all the replies.

I can get a Grundfos Magna 25-100 for no cost. It's a bit of a beast. Do you think that will be overkill or should I make use of it as it's free?

 

[doitmyself]

My system is quite large (22 radiators) and I have found, even after balancing, that the radiator furthest away from the airing cupboard struggles to get very warm.

I would check your balancing. The lockshields should normally be less than one turn open. Start will all LS valves half a turn open. Then make very small adjustments (1/12th turn or less). Only adjust one rad at a time, and wait five minutes for the change to work. You may even find that the pump can be turned down.

 

[Berksguy]

Would stick an 25-80 if you can adjust the pipework

I can get a Grundfos Magna 25-100 for no cost. It's a bit of a beast. Do you think that will be overkill or should I make use of it as it's free?

 

[ShaunCorbs]

no cost??

 

[king of pipes]

Bit overkill really you could end up with excessive noise through your heating pipework radiators and valves it needs sizing to your actual design of your system . kop

 

[Berksguy]

no cost??

Yes no cost. I have been offered this pump from a friend who purchased a job lot of stock from a bankrupt business.

 

[Berksguy]

Bit overkill really you could end up with excessive noise through your heating pipework radiators and valves it needs sizing to your actual design of your system . kop

I wouldn’t want to have excessive noise in the pipes etc.. I had thought that the AUTOADAPT feature would prevent this from happening.

 

[king of pipes]

Well by all means give it a try your choice bud you have nothing to loose it may need a small alteration on the pipwork . cheers kop

 

[Berksguy]

After seeing how large the Magna 25-100 is (it's about the size of a small family car), I've decided to go with a UPS2 25-80 and have managed to source one for a very good price. This is similar in size to my existing pump and will be easier to fit in, as space is a bit tight in my airing cupboard.

I am looking for a recommendation for a heating engineer to carry out the adjustments to fit the pump. I will also want to add a Magnaclean and an auto bypass valve at the same time. So if any can recommend someone who carries out work in the Reading area then please let me know?

Steve

 

[doitmyself]

An auto-bypass can only be used if the pump is set to a fixed speed. It is incompatible with proportional pressure as the bypass will open more as the pressure increases.

However, the flow/head curves for the UPS2 25/80 are 'flat' up to a flow of 2 to 3 m³/hr, which is equivalent to 23 to 35kW (at 10C differential) or 46 to 70 kW (at 20C diff), depending on pump speed. This means that any auto-bypass will be either open or closed all the time (depending on setting). So an auto-bypass, on its own, is effectively unusable with this pump in most domestic situations.

The way round this is to run the pump in proportional mode and have a fixed flow valve (e.g Taconova Setter) in series with the auto-bypass. The bypass will open at the required setting but the flow will be restricted by the Setter valve.