Quick quesiton on replacement CH Pump specs - Gravity Fed

[Boff]

Hi, I'm going to replace the pump on my CH system as it's died.
CH/HW has been off & drained down for over a month while I've replaced some of the rads. Refilled and fired everything up tonight but the pump isn't running.

It went about a year ago but after removing it and beating the **** out of the pump body it worked again!

I suspect it's probably seized or something due to there being no water in it for so long?

Anyway....
What does Max Head Delivery mean? And should I pay attention to it when purchasing a new pump?

Is it:
Distance from boiler/pump to F+E tank? (Pump is right next to boiler)
Distance from boiler/pump to highest rad?
Distance to HW cylinder?
None of the above?

Anything else I need to be aware of before I purchase a replacement?

I think the current pump may be a Grundfoss but don't quote me on that.
I'll know for sure tomorrow night when I've had a proper look. I'd rather get a new one than fannying about with one I have, as I knew I was on borrowed time after the first incident.

More info:
Gravity Fed
Gloworm Hideaway boiler
Pump is on vertical pipework situated right next to boiler, and pumping IN to the boiler.
Boiler/Pump in cellar below ground floor.

If anyone needs more info/pics please let me know.

Cheers
Boff

 

[Garygas69]

Hi, I'm going to replace the pump on my CH system as it's died.
CH/HW has been off & drained down for over a month while I've replaced some of the rads. Refilled and fired everything up tonight but the pump isn't running.

It went about a year ago but after removing it and beating the s**t out of the pump body it worked again!

I suspect it's probably seized or something due to there being no water in it for so long?

Anyway....
What does Max Head Delivery mean? And should I pay attention to it when purchasing a new pump?

Is it:
Distance from boiler/pump to F+E tank? (Pump is right next to boiler)
Distance from boiler/pump to highest rad?
Distance to HW cylinder?
None of the above?

Anything else I need to be aware of before I purchase a replacement?

I think the current pump may be a Grundfoss but don't quote me on that.
I'll know for sure tomorrow night when I've had a proper look. I'd rather get a new one than fannying about with one I have, as I knew I was on borrowed time after the first incident.

More info:
Gravity Fed
Gloworm Hideaway boiler
Pump is on vertical pipework situated right next to boiler, and pumping IN to the boiler.
Boiler/Pump in cellar below ground floor.

If anyone needs more info/pics please let me know.

Cheers
Boff

If its a normal two storey house buy a 15/50 pump grundfos are best but what the heck

 

[TicklyT]

The maximum delivery head is the pressure difference between the inlet and outlet of the pump when it is running with minimum flow. It has little, if anything to do with the static pressure at any point in the system.

The pump speed adjustment controls the pressure and flow rate of the output.

Some poorly designed or maintained systems may be prone to either 'pumping over' or drawing air down the open vent if the delivery pressure is too high.

 

[Boff]

Thanks for the replies,

When checking the specs of replacement pumps it says Max Head Delivery 4.5m/5m/6m etc. It does not mention pressure or pressure difference.


House is a normal 2 storey semi yes, but boiler and pump are below ground floor in cellar. (So it's a 2.5 storey house at best!)


So I don't need to worry about Max Head Delivery and just get a pump that does CH?

Been looking in Screwfix and there's a Wilo Smart Pump ~£50, Suitable for CH, with 6m Max Head Delivery. I'll have a quick check of the Grundfoss ones now.

 

[Boff]

Christ those Grundfos pumps aren't cheap are they!

Looking at two - there's only a 6 quid difference between them:
Grundfos Alpha+ 15-50
Grundfos UPS15-50

I really can't afford anything better as I've just forked out for new rads downstairs. (Not to mention inhibitor and noise reducer - what a waste that's going to be!)

What about Pegler or Flomaster? Any good?

 

[Garygas69]

Christ those Grundfos pumps aren't cheap are they!

Looking at two - there's only a 6 quid difference between them:
Grundfos Alpha+ 15-50
Grundfos UPS15-50

I really can't afford anything better as I've just forked out for new rads downstairs. (Not to mention inhibitor and noise reducer - what a waste that's going to be!)

What about Pegler or Flomaster? Any good?

Don't know about those 2, can't recall seeing them before. Don't know if it's any help but Plumb Center had a pack of 2 Myson pumps on offer about 60 quid.

 

[45yearsagasman]

If your budget can stretch to it then most guys on here would go Grundfos 15/50.Good reliable pump when correctly installed and vented correctly.Start off on speed 2.

 

[outinthestix]

Boff wrote (Not to mention inhibitor and noise reducer - what a waste that's going to be!)
No need to waste your inhibitor and noise reducer. Just turn off the pump valves and swap the pump without draining down.

 

[Boff]

Thanks for the advice but I forgot to mention that one of the valves is stuck fast on the pump (remembered from last time I removed it) so it'll have to be a drain down and new gate valve. I changed the other one last time the pump was removed.

A bloke in work has given me a Myson Unit Five he had laying about, it's unused and brand new apart from it's age. Bought a new gate valve (aswell as more inhibitor & noise reducer!) so I'll swap them either one night this week or on the weekend.
*Edit- So worst case scenario the new pump is broken so I'll have to buy one anyway.

Put the CH on again tonight when I got home and cranked the pump right up and give it a few bangs for good measure. I think it's running again, turned boiler off and it felt like the pump was spinning. The CH is still on now (been about 2.5/3hrs) and all the upstairs rads are hot but most of the downstairs are cold!

All the rads downstairs, 4 in total, are the ones I replaced. I thought the downstairs rads came on first but now not sure of the order. The rads have NOT been balanced yet but surely there'd be a bit of heat getting to them or residual heat in the pipes. 3 are stone cold and so are the feeds.

TRV's (newly fitted to all the new rads) are on max (a triangle shaped symbol pointing towards a line, like a reversed 'K'). The lockshields were all on half but now I've fully opened them all to try and get some flow going through the rads.

It's as if there's not enough heat to go round.

Could the pump be causing this if it's knackered? Just want to make sure everything's tickety-boo.


I'm thinking of closing off all the rads, then opening each one in turn just to make sure they work. There's definitely water in them all as I bled them yesterday when refilling the system.

Ha ha so much for the quick question!!
Sorry for the length!

P.S. All new rads are either of equal size or smaller than the old ones.

 

[Boff]

Just had a quick look through the plumbing faq and it seems like the cause could be the pump, or possibly an airlock, or possibly balancing?

It's a twin pipe system (feed and return are on 2 different pipes)

I am going to balance them, but just wanted to get the heating back on as it's been off and empty for so long with all the DIY.

The balancing 'project' I was going to leave for another day! After lots of research on here, obviously ;o)

 

[Boff]

Sorry - one last thing!

System had been cleaned with Sludge Remover and flushed (fill and empty, not a 'powerflush' or anything) about 4 times. All upstairs rads were removed and flushed with a hosepipe prior to CH going back on (but after the cleaning and flushing of whole system)

So it's as clean as it's ever been. Didn't want to get **** in my new rads!!

But if it's been empty for a month or two, could that cause more oxidation/sludge?

The order was: cleaned, flushed x4, used CH for ~1 week, CH system empty for ~2 months, removed and flushed upstairs rads, fitted new rads downstairs, CH back on.

 

[Homesafe]

You talk too much, has anyone ever told you that? get the other pump on an let us know what happens.

 

[Boff]

Ha ha!
Just trying to answer all the questions before anyone asks!!!

Pump will be changed tonight.

 

[Boff]

Just posting to say I installed the Myson pump and all is good! Rad heating is a bit all over the place but hopefully a bit of balancing will sort that out.

Put a new valve in aswell so at least I won't have to drain down in future.

Thanks again for everyone's advice and sorry for all the posts!

Cheers
Boff