Central heating pump - help

[MattH]

I have recently moved into a larger house and am having soem problem

with the radiators not getting hot, i have tried balancing which ha helped but really my question is, is the pump i have strong enough. Th house has 23 radiators of which 18 are large doubles, the pump is grundfos 15/60, which i understand is a powerful domestic model, but cant help thinking isnt up to the job.

Can anyone advise whether i can install a more powerful version, if s what, or how can i check that this is strong enough, i cant hel feeling it isnt.

Thank

-- MattH

[Dave Liquorice]

Does the boiler have sufficient output for that number and size of rads?

[Set Square]

You are probably asking the wrong question. Pumps don't generate heat - well, not very much anyway - they simply distribute the heat generated by the boiler.

So the first question needs to be whether the boiler is big enough.

When the system is on, is the boiler running continuously? Are there any room thermostats? If so, what temperature are they set at?

If the boiler is running flat out this time of year, you haven't got a prayer in the winter!

If the boiler is cycling on an off but the rads aren't very hot, it *could* be the pump - or it could be the control system turning the boiler off when it thinks the house is hot enough.

Is the *house* cold - or just the rads? If the latter, the system *may* be doing its job properly.

[Chris Bacon]

Kinell.

[Rob Morley]

Do the servants have central heating too, or do they just have to work hard to keep warm?

[Owain]

An idle browse around primelocation.com reveals a large number of most attractive chateaux in France with about 20 bedrooms that can be had for the price of a modest pied-a-terre in Mayfair.

Owain

[Alan]

I wouldn't say 23 rads is that excessive - I live in a modest 3-bed detached and that has 13!

It could be that the radiators are sludged up at the inlet - in a previous house, I had large double rads that didn't heat up until the heating had been on for hours - they were almost cold to touch at the inlet, but the pipe was very hot. They were sludged up quite badly - after remvoving them and hosing them out we found they heated up to a good temp.

[look]

What is the boiler thermostat set to ? Is it turned up near max. Do any of the radiators get hot ? If you turn half them off , do the other sget half ?

Robert

royall at which net

[Doctor Drivel]

Lots of elbows can defeat it. Otherwise put another pump in series (two together). This will get the pressure up. I have seen a pump on the flow and one on the return and that worked quite well. The boiler can act as a big restrictor to flow. One pumping into the boiler and one pumping out.

It will be better if you split the system up into two zones. Say, upstairs and downstairs, and have a pump and non-return valve on each. Grundfos do twin pumps sets for this. Then you divide the system up. You can also have each zone on separate temperature stats and timers. Upstairs can be off during the day and only on during bedtime and in the mornings. This is the best approach as it solves the problem and saves on fuel bills.

[Set Square]

Perhaps I should emphasise that having twin pumps isn't a pre-requisite for zoning. It is perfectly feasible - indeed more common than not - to have a single pump for multiple zones. After all, you're only going to have one boiler - or *are* you?!!!

[Doctor Drivel]

You must learn to focus. The problem appears that the pump is not man enough. Using two to great effect and also give zoning, which saves energy and lowers bills is the way. Got it?

Or two system boilers with their own integrated pumps for each zone also, if the boiler also is not man enough. Got it?

[Ed Sirett]

If the rads are not getting hot - then the question is what is the boiler doing.

A) Flat out alway s running - i.e. it's not powerfull enough for the 23 rads. OR B) The boiler is getting very hot but there is not distribution of the heat to the rads this can be any number of problems. And 'pump needs to be bigger' is at the end of the list.

[Set Square]

On the contrary, *you* must learn to focus.

Suprisingly(!) I was not saying that yours was not a valid solution - but simply that it wasn't the *only* valid solution.

Let's not lose sight of the fact that these posts are read by many people - not just by those who ask the questions - and I wouldn't want anyone to jump to the conclusion that you *have* to have multiple pumps in order to achieve zoning. Your previous post could have been interpreted thus.

[Doctor Drivel]

You must learn to focus. His pump appears too small for the system. The next size up is very "expensive", so doubling up is in order. Adding another pump can also zone off. Got it?

Exactly and I hope they don't take much notice of you.

[Set Square]

I suspect that most of the regulars are sufficiently discerning to know whom they can trust - and I don't imagine that 'Doctor Drivel' features on their list - except as a source of entertainment.