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.

 

[Berksguy]

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.

Thanks for your detailed reply. Currently the bypass in my heating system is via a towel radiator in a bathroom. Do you think it would be best to keep it this way or move to the auto bypass and setter solution?

 

[ShaunCorbs]

Thanks for your detailed reply. Currently the bypass in my heating system is via a towel radiator in a bathroom. Do you think it would be best to keep it this way or move to the auto bypass and setter solution?

depends if you go fixed speed adjustable pump then have a separate bypass fitted if you go for a load adjustable pump then no need

 

[doitmyself]

Currently the bypass in my heating system is via a towel radiator in a bathroom.

What makes you think the towel rad is a bypass?

There are only two reasons for a bypass:

1. The boiler manufacturer says it is necessary;
2. To provide a path when all motorized valves are closed and the boiler has pump overrun.

You haven't said which boiler you have or anything about your system, so I don't know which applies.

 

[Berksguy]

What makes you think the towel rad is a bypass?

There are only two reasons for a bypass:

1. The boiler manufacturer says it is necessary;
2. To provide a path when all motorized valves are closed and the boiler has pump overrun.

You haven't said which boiler you have or anything about your system, so I don't know which applies.

When the boiler was originally installed the plumber told me to never turn off the one towel radiator as it was the bypass for the boiler.

The boiler is a Potterton Suprima 120L.

Steve

 

[doitmyself]

The Suprima 120L has pump overrun. The MI's suggest either an auto bypass valve or a bathroom rad/towel rail to give the required circulation when motorized valves are closed. In either case, it has to be connected to the flow between the pump and the MV. If the towel rail solution is used there is a permanent flow through the rail, even when towels don't need to be heated. Replacing the towel rail with an auto bypass would be better; but then there's the problem of heating the towel rail. It would need connecting to either the CH or HW flow after the motorized valve(s).

I have assumed that you have two motorized valves. If you have only one mid-position valve (3 pipes connected), you don't really need a bypass as one port is always open.

The MI's also say that a large domestic/small commercial pump is required due to the high flow rate and large pressure drop through the heat exchanger. The UPS2 25-80 is not ideal, but it will work.

 

[Berksguy]

The Suprima 120L has pump overrun. The MI's suggest either an auto bypass valve or a bathroom rad/towel rail to give the required circulation when motorized valves are closed. In either case, it has to be connected to the flow between the pump and the MV. If the towel rail solution is used there is a permanent flow through the rail, even when towels don't need to be heated. Replacing the towel rail with an auto bypass would be better; but then there's the problem of heating the towel rail. It would need connecting to either the CH or HW flow after the motorized valve(s).

I have assumed that you have two motorized valves. If you have only one mid-position valve (3 pipes connected), you don't really need a bypass as one port is always open.

The MI's also say that a large domestic/small commercial pump is required due to the high flow rate and large pressure drop through the heat exchanger. The UPS2 25-80 is not ideal, but it will work.

Thanks again for your detailed responses.

There are two separate motorised valves in my system. The towel rads coming on when the hot water is being heated is usually a good thing. However, on the few summer days where we get high temperatures, it would be useful to be able to turn off the radiator.

What would you suggest as an alternative to the UPS2 25-80?

Steve

 

[doitmyself]

There are two separate motorised valves in my system. The towel rads coming on when the hot water is being heated is usually a good thing. However, on the few summer days where we get high temperatures, it would be useful to be able to turn off the radiator.

So you will need an auto bypass to take the place of the towel rad, which will need its flow moved from after the pump to after the HW valve.

What would you suggest as an alternative to the UPS2 25-80?

The 25-80 will be fine. It's just that the pump will not be working at the optimum point on its flow/head curve, so running costs will be slightly higher.

 

[Berksguy]

I arranged for a heating engineer to call around yesterday to have an initial look at the work I need undertaking. He didn't turn up and when I rang him he provided a feeble excuse for not coming. So I'm still looking for a good heating engineer that carries out work in the Reading area.