UFH System Question - Help Needed

zorch

Help Wanted

I'm in a house two years, bough new, with Gas UFH downstairs - Rads upstairs and the boiler also heats the Tank for bath showers etc.

Now fed up with system as to maintain any heat downstairs - leaving the UFH on - costs me about 600 Euro per 2 month bill. Now having to leave off the rooms we don't use. In summer we dont seem to need the system on at all - only for water. In fairness I feel 18 is too cold we generally like it to be 20-21C - so know It will cost more with that setting - but not that much.

System is set to only come on 4-5 hours in the morning and same in the evening - I'm afraid of my life to leave it on 24*7- in case of a serious Gas bill! and the arse falls out of the temperature overnight. House is reasonably well insulated.

House is about 300m2. Looking previous threads - The system is sending out water to the UFH at about 40C and return is about 30C. Everything seems balanced and functioning - although Rads upstairs never get very hot. In the morning the circuit for the hot water tank takes nearly an hour to be warm enough for a shower.

Floor between upstairs and downstairs is concrete - so dont really get any transfer of heat from downstairs to upstars rooms either

Looking at the boiler it is an Ideal Mini (S28) - this does not seem to be a condensing boiler - could this be a source of my problems. Any digging i do shows that a standard boiler should run at approx 80C,

Is the boiler or it's setup the problem? Anyone know a good heat /Energy consultant?

any help appreciated

ircoha

Not certain of what comes next but from this link:

http://www.vhsdirect.co.uk/site/product.cfm?id=26CE8E08-9FA2-8E4F-3515E74D1DAE07AB

it seems, and I stress the seems, that the S28 is a combi boiler and therefore produces produces HW directly and not indirectly so there is no need for a HW cylinder. maybe it is being fed from the CH circuit

It is not clear whether there are 2 stats on it, the CH circuit can be set up to 85 but the water seems set at a max of 35.

UHF is designed to run at low temp so you could not really run it at 80 degrees you would prolly crack the screed!

The rads wont get too hot as they are running on 40 degree water but may have been sized for a higher inlet temp

In fairness I feel 18 is too cold we generally like it to be 20-21C - so know It will cost more with that setting - but not that much.

each degree drop in temp saves about 10% at these levels: IMO that is 'much'

A condensing boiler is just more efficient, that is not the issue here ...yet:)

sinnerboy

I would have a nasty feeling that maybe the ground floor insulation may be in the wrong place .

Correct construction layers is
75 screed with UFH pipes
Insulation ( should be 100 thick )
150 concrete sub floor

A bad contractor may build
Screed with UFH pipes
150 concrete sub floor
Insulation
this way the UFH uselessly heats the 150 conc

OR
another mistake is to place timber flooring over a layer of plywood over the screed - i.e. too much insulating timber material over the UFH

You should not be consuming so much fuel for so little benefit

zorch

I saw the floor and UFH system going in, looked fine, don't recall membrane to external wall at time of top layer screed . But sub insulation looked correct (pollystyrene). Most of downstairs is Marble, worst room is wooden floor over concrete - no battons, and using non foam based membrane ( requested for UFH). External walls constructed using two layer of block - with Kingspan ( looks about 80mm). Plaster board fixed using plaster blobs ( not battons) plaster board feels very cold on external walls.

sinnerboy

sounds like you do need a good plumbing guy to review the installation

have you tried to contact the installer ? he should be able to correct problems , if he is any good