Central Heating

[st3v3]

In Bld Regs L1 2002 there is requirement that no heating zone is bigger than 150sqm. Could someone confirm if that requirement is still valid. 2002 is an old Reg and I can't find reference to the requirement in later versions.
Also noticed on Honeywell & Drayton websites that new homes must now have twin heating zones (upstairs/down) irrespective of floor area, is that true and could someone point out which Reg it's in please.
thanks steve

 

[D_Hailsham]

The latest version of Approved Document was issued in October 2010. Much of the detailed information is now in the Domestic Building Compliance Guide 2010.

All new buildings below 150m² must have at least two zones with independent temperature control, unless they are single storey with over 70% living space.

Buildings over 150m² must have at least two zones with separate time and temperature control. But this is, apparently, being reviewed.

The requirement for no zone to be more than 150m² has been dropped.

Whether, and when, existing systems need to be updated, e.g on replacement of boiler, is the subject of much debate. The general consensus is: no.

 

[st3v3]

Many thanks for very rapid response. We moved into a new house in June 2011 in which foundations were laid in early 2011. The heating system was installed in April 2011. It only has a single heating zone and external wall-to-wall area is 161sqm ('usable' area might be less than 150sqm). We do struggle with the temperature variations in some rooms. From what I read, the system seems to be non-compliant. Would appreciate your opinion on whether you agree that it is?
Thanks again for previous advice - very much appreciated!
regards Steve

 

[D_Hailsham]

There were transitional provisions which said that, if approval was sought before October 2010 and the work was completed before October 2011, the 2009 Regulations still applied. These did not require two zones.

161m² external is probably less than 150m² internal!

I think the builders have got it right; but if you want a definitive answer, contact the Building Inspectors at the Council Offices.

Where is your room thermostat located?
Do you have thermostatic valves on all rads (except where room stat is located?

 

[st3v3]

Thanks again.
I should have said that the house is a conventional 2 floors (but think you guessed that), 4 bedrooms upstairs.
Thermostat is in the hallway, at the start of the stairwell.
There are 15 rads in the house, 3 towel rails - one in each ensuite. 5 rads in the 4 bedrooms - it is only these 5 bedroom rads that are fitted with TRVs.
regards Steve

 

[st3v3]

Correction...there are 18 rads in the house...

 

[swbjackson]

TRVs should have been fitted to all radiators bar the one in the area with the room stat. This has been a requirement for some time.

 

[ALEC1]

is the system properly balanced?

 

[D_Hailsham]

TRVs should have been fitted to all radiators bar the one in the area with the room stat. This has been a requirement for some time.

It may be the current requirement, but there is no obligation for existing systems to be updated. Though it is recommended when the boiler is replaced.

It sounds as if the thermostat in the hall is turning the boiler off before other rooms have got up to temperature. Firstly check the balance of your system.

Set all TRVs to max and turn the room stat up to, say 25C ( to keep the boiler on). Then let the system heat up for 10 minutes or so. Check, by feel, how warm each rad is; they should all feel the same temperature. If there are noticeable differences the system needs balancing. See How to balance a CH system.

Do you have a very large radiator in the hall, possibly heating the upstairs landing as well? If so you should shut this radiator down so it takes longer for the hall to heat up, thus keeping th boiler on for longer and giving the other rooms a chance to reach temperature.

If this doesn't work, your system is undersized, which is unusual.

If that is the case, check the size boiler you require, using the Whole House Boiler Size Calculator and check the output of your radiators using Stelrad Elite Catalogue

 

[st3v3]

I do accept that system balance is likely to be a factor. I have considered trying to balance but when the input temp is 80degC, both sides of the rad is b****y hot to the touch - I'd benefit from having the right tools!
Alec's comment about TRVs should be fitted to all but room stat rad (and except bathrooms?) is interesting given the date when we moved in (Jun11) and I will take up with the Builder.

It's a David Wilson Home (aka Barratt) and support is very good. I've managed to get the Customer Services Mgr from York, the independant specialist that designed the system from Newcastle and a chap from the boiler manufacturer (Ideal in Hull) paying me a visit next week to investigate and discuss, so will put all these issues to them.
I'll be asking about the Building Regs (whether it should have been 2 zone..), and the TRVs. I'll also ask them if they'll balance the system.

I have calculated the entire house heat loss based on U values from a lot of website trawling. The rads are Stelrad Elite's so found the spec for those. The heat input calculates at well adequate at outside air temps of -1c and I think the problem may be to do with significant heat loss (~300W @-1C outside) through floor of bedrooms into integral garage below.
I still like my plan of getting another zone added for upstairs, but they may want to better insulate the bedroom floor/garage ceiling - which I accept might be the root of the problem.
Will advise when they've been next week.

I have to say that responsiveness and help from this site is INCREDIBLE. You've all, esp D_Hailsham, been brilliant...THANK YOU!!!!!
regards
Steve

 

[st3v3]

sorry swbjackson....it was your comment on TRVs...!!!!!! Thanks!!

 

[swbjackson]

TRVs should have been fitted to all radiators bar the one in the area with the room stat. This has been a requirement for some time.

It may be the current requirement, but there is no obligation for existing systems to be updated. Though it is recommended when the boiler is replaced.

This is a new build though so they should have been fitted.

 

[D_Hailsham]

This is a new build though so they should have been fitted.

You are quite right.

The Domestic Heating Compliance Guide 2008, which would have applied to the house says:

Dwellings up to 150m² should be divided into at least two space heating zones with independent temperature control.

Separate temperature control of zones should be provided using:
1. Room thermostats or prog stats in all zones; OR
2. Room stat or prog stat in the main zone and individual radiator controls such as TRVs on all rads in the other zone; OR
3. A combination of 1 and 2.

The problem is the vagueness of individual radiator controls such as TRVs. A wheel valve is one example of an "individual radiator control"; a TRV is another example. If the authors wanted to insist on TRVs they should have said so.

Again, this is a matter to take up with the Building Control Officer.

 

[st3v3]

There were transitional provisions which said that, if approval was sought before October 2010 and the work was completed before October 2011, the 2009 Regulations still applied. These did not require two zones.

I've spent a few hours reading through the all the regs I can find, but can't find any evidence of the above quote.
ADL1A_2002 states that no heating zone to be larger than 150sqm.
ADL1A_2006 references the Domestic Heating Compliance Guide_2006 which states that at least 2 zones should be installed irrespective of floor area.
DHCG_2008 references ADL1A_2006 (I think) and states 2 zones same as DHCG_2006.
ADL1A_2010 references the DBuildingServicesCG_2010 again states 2 zones same as DHCG_2006.
I don't know what date the regs would have been made applicable on my house...I'll find that out.
If it's possible to point me to the transitional provisions above I would be most grateful (if they are online), also I've found no regs dated 2009 ?
regards
Steve

 

[D_Hailsham]

There were transitional provisions which said that, if approval was sought before October 2010 and the work was completed before October 2011, the 2009 Regulations still applied. These did not require two zones.

I've spent a few hours reading through all the regs I can find, but can't find any evidence of the above quote.

It's in the Building Regulations 2010 Part 10, paras 50 to 53.

You have been looking at the Approved Documents and the Compliance Guide, which are one step and two steps further down the legislative chain: Building Act (1984) - Building Regulations - Approved Documents - Compliance Guides. The further down the chain you go, the more detailed the information provided.