We're in the middle of a major (and sadly very expensive) renovation. It's a big old place with 16 rooms over 3 floors which we hope to run as a B&B. We've had a new heating system installed so that means a new boiler, 350L tank and approx 27 radiators. 3 of the ground floor rooms have underfloor heating.
We've ended up with 7 pumps and we wonder whether this is the correct and most efficient thing to do? The boiler/ tank installers fitted 2 pumps and then handed over to another firm for the installation of the rest of the system.
When the second floor radiators didn't warm up this second firm added 3 pumps from the valved off pipe work:
a) Pump one feeds Zone 1 of the heating system (front of the house)
b) Pump two feeds Zone 2 of the heating system (back of the house)
c) Pump three feeds the underfloor heating system.
The plumber says it was necessary to fit three pumps as the valves were already in place.
They say that had just the one valve left for them they could have installed just one pump, "however this would have been a very expensive option" (he didn't explain why).
Then they installed a further two pumps to:
a) Feed the hot water return
b) Feed the underfloor heating which is required by Polypipe to circulate the heat under the floor.
Does this seem the right thing to do? We're worried that what is supposed to be an energy-efficient system is going to cost us an arm and a leg in electricity powering all those pumps? Should we be worried or not?
Many thanks to all you experts out there who understand all this and can give the benefit of your advice.
The only guide I can give you is that a house I regularly work on has 17 rooms, the pipework out of the boiler is 1.5" and the whole system including two HWC are fed by one grundfos 25-80 pump.
7 pumps would therefore seem a bit excessive - you will clearly need someone who understands heating systems very well to sort this out.
I would have thought the original 2 pumps plus one for each underfloor heating grid would be enough.
Thanks so much for that info. That's pretty much in line with what we thought. It's a bit difficult to know where to go from here as the plumbers seem reluctant to do any more work until we've settled the account for these 3 extra pumps. The invoice is a bit steep too. £460 for the pumps and fitting which took 2.5 hours. We notice you can buy the pumps for a total of £180 online.
Can I ask you one other question? Do these oumps use a lot of elecricity? We've swapped oil for wood pellet so it would be ironic if we now have vast electricity bills!
Cost of the job is difficult, your plumber probably charges £50+ per man per hour, add isolating valves for each pump = £100 plus other materials
plus VAT on top.
A good average would be 60w per pump and it is unlikely that all would be running at the same time. If you are on full price electricity allowing for diversity the pumps could be costing you 5p - 10p per hour - they'll run more in the cold weather. This doesn't sound much but run the CH for 8 hours a day and your quarterly bill for the pumps alone will be £40 - £80.
Hope that helps.
Cripes £80 a quarter! Sounds like we definitely need to get this changed then. No point burning wood pellets in an attempt to be green and then sucking thousands of kilowatts off the national grid!
Thanks so much for this info. No-one else has been able to even give us an approximation of how much electricity it takes to power these pumps. I think we'll have to get someone impartial in to take a look at how it's set up currently and come up with a more economical solution.