Help with Part L zoning requirements for new build

[Saltdean]

Hi, Do any of you guys work regularly on new builds? Just staring my first ones (six) since the revised part L came into force. I'm just looking for some clarification on zoning requirements, before i go and make a fool of myself.
The total useable floor area is less than 150 m3 (actually 120m3) so as i understand it I don't require seperate timing for the Zones, the bit that i'm a little uncertain about is the actual zoning. In the on line compliance guide it states that seperate space heating zones are required, so assumed i'd need to use an s plan arrangement with two stats and a single channel programmer, however... further on under the heading of "temperature control of space heating" it appears to give the option of a room stat/prog roomstat in the main zone and trv's everywhere else? (as in replacement job's) can anyone confirm that this is the case?

 

[Saltdean]

Forgot to add, they're combi's so obviously no hot water zoning required.

 

[powervan man]

You have to fit a room stat upstairs and downstairs with a single channel time clock 2 zone valves and TRV's to comply ,its bonkers i know .

 

[dancinplumba]

cos its new install you have to zone,
as its under 150m2 you can do it with one zone valve for upstairs controlled by stat, suggest main bedroom, rest of rads trvs.
downstairs you have progstat in one room, rest of rads have trvs.
downstairs turns boiler on and off, upstairs stat opens valve but doesnt fire boiler
imo 🙂

 

[AWheating]

the 150m2 rule was basically removed in 2010 when part l was reviewed. it now goes on type of dwelling and number of room/open plan design if i remember correctly.

as its new build there should be detailed layout plans with pipework run etc to guide you.

 

[doitmyself]

the 150m2 rule was basically removed in 2010 ...if I remember correctly.

Your memory is letting you down: the 150m² rule is alive and kicking. The only exception is for single storey dwellings where the living area is more than 70% of the total. In this case zoning is not required.

 

[Roger Welton]

Whilst its not a requirement for separate time and temp control of both zones (under 150m2) I would just use 2 programmable room stats anyway, saves having to have a timer so not much more costly.

 

[AWheating]

Your memory is letting you down: the 150m² rule is alive and kicking. The only exception is for single storey dwellings where the living area is more than 70% of the total. In this case zoning is not required.

what i ment was its no longer the rule to say that a property under 150m2 does not require zoning and a property above 150m2 will require zoning.

the only thing the 150m2 relates to now is time controls which will not really effect the first fix plumbing.

 

[doitmyself]

what I meant was its no longer the rule to say that a property under 150m2 does not require zoning and a property above 150m2 will require zoning.

the only thing the 150m2 relates to now is time controls which will not really effect the first fix plumbing.

The rules are, if anything, more restrictive! All properties, irrespective of size have to have at least two temperature-control zones, except single storey with >70% living space. Separate time control zones, as you say, only apply over 150m².

What is not clear is whether you are supposed to have a third zone if it is over 300m² and so on.

Nobody has picked up the advice in the Guide which says that, for dwellings over 150m²: "it would be reasonable to provide more than one hot water circuit, each with separate timing and temperature controls."

 

[dontknowitall]

It does make me wonder if this 150m2 rule is effective.

When you're heating downstairs you're burning more fuel as much of the heat is escaping upstairs so, to warm downstairs, more fuel is burned to compensate for this heat loss. And us humans will not want a cold upstairs so we'll make sure the heating is on properly to heat upstairs, which usually means using excess fuel.

And then, what about raw materials? Much more pipework, wiring, extra controls and so on. Then there's more petrol consumption as the job takes longer, more electricity used for drills, light, etc and so on.

Perhaps it would be more effective (and use less materials) to install slightly under-sized radiators upstairs?

Whatever the case, proper insulation and radiator sizing should negate the need for all this zoning.

Hmmph!!

 

[Roger Welton]

At home when the boiler was replaced a few years ago I zoned off upstairs, I find it works well, we delayy the heating coming on until later in the evening, then it doesn't take long to get to temperature. In the autumn and spring we just have upstairs on to take the chill off in the mornings.

From pre-change to post we noted about a 40% drop in fuel consumption, that was taking into acount replacing the boiler and converting from gravity hot water as well.

 

[doitmyself]

It does make me wonder if this 150m2 rule is effective.

When you're heating downstairs you're burning more fuel as much of the heat is escaping upstairs so, to warm downstairs, more fuel is burned to compensate for this heat loss. And us humans will not want a cold upstairs so we'll make sure the heating is on properly to heat upstairs.

I think the authors of the Guide assume that all doors are kept closed, except when someone is entering/leaving the room, so you can set a lower temperature (18°C) in upstairs rooms.

 

[mikeygas]

SaltDean, can you push back these jobs until after April? Reason being that there is currently an on-going Part L consultation group looking into the effectiveness of having 2 heating zones on props under 150m2, i.e there is no evidence to suggest that having more zones is anymore efficient than the "old" pre october 2010 way. Results are due at end of April.

p.s I don't know of anyone who is bothering to zone like the current regs suggests in Manc.

 

[doitmyself]

there is currently an on-going Part L consultation group looking into the effectiveness of having 2 heating zones on props under 150m2

Where did you learn this? I can't find anything online about it - can you provide a link?

 

[AWheating]

i know they are currently consulating on the next revision of part l which is due in a year or two which is going to probably upset alot of us, but i did not know it was looking into the zone debate.

 

[Roger Welton]

i know they are currently consulating on the next revision of part l which is due in a year or two which is going to probably upset alot of us, but i did not know it was looking into the zone debate.

Not looking forward to the next revision, I can't imagine it will make for an easy life.

 

[mikeygas]

I read it in one of the trade rags, I'm sorry but can't remember which one 🙁

 

[fuzzy]

You have to fit a room stat upstairs and downstairs with a single channel time clock 2 zone valves and TRV's to comply ,its bonkers i know .

anyone have a wiring diagram for this?

 

[fuzzy]

It does make me wonder if this 150m2 rule is effective.

When you're heating downstairs you're burning more fuel as much of the heat is escaping upstairs so, to warm downstairs, more fuel is burned to compensate for this heat loss. And us humans will not want a cold upstairs so we'll make sure the heating is on properly to heat upstairs, which usually means using excess fuel.

And then, what about raw materials? Much more pipework, wiring, extra controls and so on. Then there's more petrol consumption as the job takes longer, more electricity used for drills, light, etc and so on.

Perhaps it would be more effective (and use less materials) to install slightly under-sized radiators upstairs?

Whatever the case, proper insulation and radiator sizing should negate the need for all this zoning.

Hmmph!!

in theory if you set temp at 21 with downstairs stat and rads all get warm, the upstais will get warmer, therefore when stat turns off the upstairs if several degrees hotter than owners want it to be. if you can set zone upstairs lower it shuts off quicker

 

[dontknowitall]

in theory if you set temp at 21 with downstairs stat and rads all get warm, the upstais will get warmer, therefore when stat turns off the upstairs if several degrees hotter than owners want it to be. if you can set zone upstairs lower it shuts off quicker

I'm happy to go along with that but isn't that what trvs are for? A rather simplistic argument, I must admit!

 

[Roger Welton]

anyone have a wiring diagram for this?

From Honeywell literature

 

[larsson67]

SaltDean, can you push back these jobs until after April? Reason being that there is currently an on-going Part L consultation group looking into the effectiveness of having 2 heating zones on props under 150m2, i.e there is no evidence to suggest that having more zones is anymore efficient than the "old" pre october 2010 way. Results are due at end of April.

p.s I don't know of anyone who is bothering to zone like the current regs suggests in Manc.

when i rang up worcester bosch to ask about the wiring for 2 zones to the cdi combis and asked them why dont they have a plug in control for more than one heating zone i was told something similar to you that their people were having a meeting about it all and that in a month or so the 150m2 reg would be done away with

 

[Roger Welton]

when i rang up worcester bosch to ask about the wiring for 2 zones to the cdi combis and asked them why dont they have a plug in control for more than one heating zone i was told something similar to you that their people were having a meeting about it all and that in a month or so the 150m2 reg would be done away with

Worcester were lobying strongly for it to not to be a requirement before also, and look how much good that did.

At the end of the day the goverment are interested in reducing the CO2 output as they (we) have masive fines to pay if the targets aren't met.