New Hot Water System

[jon26]

I am currently helping with renovating my house, big job. One of the big jobs is the new plumbing and heating system, lots of bathrooms etc..

This question relates to the pressurised hot water system. I know from my previous house how a pressurised system works for both hot water and heating systems and that the heating system needs to be 'topped up' now and again.

I have heard there are automatic pressurisation devices out there that will automatically 'top up' the CH system should it fall below a certain pressure and disable the pumps/boiler etc. In practice I would like to think the CH system won't need to be topped up that often but it would be good to have this automatic feature in the plant room.

Does anyone have any thoughts/advice on how exactly this works and which are the best ones to use i.e. manufacturer etc.

 

[cider]

you can fit an electronic pressure switch to the electric feed to heating which will cut power when pressure falls below a set point or install a automatic pressurising device which comprises of pressure switch, pump and break tank all housed in a unit. cant remember who makes them but about 700 quid and easy to install and all locked away in a nice box. usually for BIG installation though. if your revamping everything properly and have a correctly sized expansion vessel this shouldnt be necessary.

 

[spacethegas]

this is completely unnecessary in the domestic situation.

if the system requires topping up regularly & is not carried out manually there will be a problem that requires attention this will not necessarily be picked up & could cause a lot of damage.

+ without looking it up i suspect it would contravene water regs.

 

[jon26]

There are a few manufacturers that do these units.

A couple here:

http://www.arrowvalves.co.uk/productdetail.php?id=2

http://www.mikrofill.com/products_efd.php

I understand they are not normally fitted on normal domestic systems, but this is a very large house and I have seen them fitted before, they have a little display which shows the current CH pressure I think.

Are you saying they are normally fitted to commercial projects?

 

[spacethegas]

my guess is that “non-house” gives it away.

but i have no doubt you will receive a definitive answer from someone who really knows their onions.

to be honest i would be interested to know.

 

[jon26]

Yea, I will look into this and keep you posted. It does say 'non-house' and also systems over 45kW (which it will be), looking at a 65kW boiler.

Have you seen them on larger systems before anywhere?

 

[spacethegas]

only on industrial, commercial & large oap complexes.

 

[simond]

A 65Kw domestic is not that large and we would not usually fit a pressurisation unit in this instance.

For larger commercial stuff you do need an automated fill system but at this size it is an unnecessary piece of plant.

Most good European boilers (eg: Viessmann 200/300) in this size band are designed to work on sealed systems and have their own low pressure switch. Viessmann 300 is no longer sold in the UK, which is a shame, as it was the dogs danglies.

 

[ChrisR]

From half a dozen fitted, these filling systems seem to be disproportionately unreliable!

Afaik ALL boilers have some way of dealing with low system pressure, some better than others. Point is though, that they stop without warning.

A pressure switch set to put on a red light or beeper at a low but safe pressure as a warning, is cheap and effective.

 

[jon26]

I have been speaking to a friend today who has one fitted to his system (this comprises of 2 no. 50kW Wolf boilers), which is quite a bit larger than the proposed 65kW boiler to my new system, so I think I shall leave it out, or at least fit an indicator that comes on when pressure is low as suggested.

Just out of curiosity, are these automatic filling systems required on commercial projects if they had a 65kW system? Or would that generally be considered too 'small' a system to install one on?

Presumably an automatic system on a commercial job, even of 65kW size, would need a more 'automatic' system to be fitted??