central heating circulation pump in the loft?

[trevw]

Hi,

Is it okay to put the central heating circulation pump in the loft? It will be 1.2m below the base of the feed/expansion tank but above the hot water tank.

More details:
2 storey house with condensing Boiler in kitchen.
vented hot water tank on first floor
cold tank in loft.
28mm copper pipe for primary circuit

The pump instructions say it needs 1.3mwg of dynamic head for 75 deg c but I am unsure of exactly how to calculate this and wondered if there was a rule of thumb.

will be greatful for any help

Trev

 

[twgas]

1.2m is not an awful lot, when the pump turns on/off the surge of pressure is likely to pump over or suck in, this will cause a gradual sludge-up of your system.

 

[trevw]

thanks twgas, I had a sneaking suspicion it was pushing it - it just would have made the plumbing so much easier!

There are 2 UFH manifolds being supplied as well (have their own pumps), reading a thread I just found on here it sounds like this might result in a high volume requirement reducing dynamic head further so perhaps a doubly bad idea?

thanks again for the swift response - can get on with it now

 

[Agile]

If I had to do that then I would connect the F&E with a single pipe combined feed and vent which would probably work OK.

But its not very ideal !

Pumps are better placed towards the bottom of the house!

There is a simple solution and that is to convert to a sealed system !!!

Tony

 

[twgas]

have you thought about pressurising the system, wouldn't matter where the pump goes then, most boilers are ok for this but check yours before doing it.

 

[spacethegas]

i don't think there should be a problem as long as 22mm c/f & expansion with surge arrestor are close coupled before pump.

 

[trevw]

thanks for all the replies.. getting on with it today. Unfortunately if it's a sealed system then I can't work on it as far as I understand it and my budget is tight.

Also my wife is paranoid about sealed systems after reading some news story of a tank going bang (although if I remember rightly the system in question hadn't been maintained in a number of years)

thanks again for all the help

Trev

 

[twgas]

the sealed systems that require certicated engineers are unvented cylinders, a sealed heating system is not that. Although it is quite common to have both.

I've not known one to go bang.

 

[doitall]

Why do I get the impression of the blind leading the blind and the OP hasn't a clue.

A good book before you start Trevw is in order

 

[Agile]

the sealed systems that require certicated engineers are unvented cylinders, a sealed heating system is not that. Although it is quite common to have both.

I've not known one to go bang.

When sealed heating systems were first starting to be used in the later 70s it was first stated that installers would need a Certificate. However, no course/assessment ever appeared and the whole idea was forgotten.

I nearly saw one go bang when the PRV was stuck and the pressure climbed to 6 Bar but the ( uncharged ) expansion vessel quietly leaked at its seams and relieved the pressure. It even resealed when the pressure was removed and only needed recharging.

Tony

 

[twgas]

When sealed heating systems were first starting to be used in the later 70s it was first stated that installers would need a Certificate. However, no course/assessment ever appeared and the whole idea was forgotten

so I was right then.

I nearly saw one go bang

but that isnt actually going bang, is it?

 

[gas4you]

Most open vent boiler manufacturers state a minimum head of 900 or 1000mm for the expansion tank above the highest point in the system pipe work.

You shouldn't have any problems, although I would frit an aerjec and make the cold feed a 22mm supply. Idealy you should have 3% of the system water volume in the cold feed.