New part L 55 degrees flow?

[Matt0029]

Stumbled across this when researching heat pumps surely this can't be true for gas boilers? And un-enforceable..

 

[ShaunCorbs]

Yep new building regs

 

[Matt0029]

So we have to oversize rads for this lower flow? The few point of natural gas is 54 degrees I believe. So a flow of 65 would be ok with a delta T of 11c.

 

[Matt0029]

Anyone work on new builds and seen this come into effect?

 

[ShaunCorbs]

A flow of 55 so return 35 ready for heat pumps eg no need to do any internal pipework alterations

 

[ShaunCorbs]

Anyone work on new builds and seen this come into effect?

Building control will have to enforce it

 

[Roy_66]

Interesting if boiler controls in future simply won't be adjustable over 55degC. If there is no reg to actually fit new larger rads then if it's left set at 55degC at the end of a new boiler job then what's to stop the owner just turning it up a bit in the depths of winter? Oh yes - the gas bill!

So in the long term also fitting those bigger rads may be in the customer's interest? (Apart from many won't have the cash up front)

Hoping for a mild winter.

Cheers,

Roy (amateur)

 

[snowhead]

Interesting if boiler controls in future simply won't be adjustable over 55degC.

According to Ideal , No.

Introducing Part L: what the new building regulations mean for you

Ideal Heating provides high efficiency boilers which include Combi boilers, system boilers and new boilers. Find an installer for a new boiler.

idealheating.com

 

[ShaunCorbs]

No as boiler manufacturer are saying what about older installations they can’t lock 55

 

[Ben-gee]

Interesting if boiler controls in future simply won't be adjustable over 55degC. If there is no reg to actually fit new larger rads then if it's left set at 55degC at the end of a new boiler job then what's to stop the owner just turning it up a bit in the depths of winter?

You misunderstand Roy, the boiler will only be set to 55 deg C where the system has been designed for this, in which case there would be no advantage to turning the boiler up a bit.
In reality this will be all new builds and most complete system replacements, but it won’t be possible in all cases so there is no way manufacturers will restrict to 55 in the foreseeable future ……

 

[John.g]

Means doubling the rad size if one runs with a dT of 10C.

What about legionella protection for DHW?, will all new boilers now have to have HW priority and increase the flow temp to 80C?.

 

[Matt0029]

You misunderstand Roy, the boiler will only be set to 55 deg C where the system has been designed for this, in which case there would be no advantage to turning the boiler up a bit.
In reality this will be all new builds and most complete system replacements, but it won’t be possible in all cases so there is no way manufacturers will restrict to 55 in the foreseeable future ……

Thanks but why are they stating a 55c flow? I usually set at around 65 if possible so should return at 54c so will condensate? Are they saying they want the full heat exchanger in condensating mode at all times?
Or is it more design your system to run at 55c flow temp. So can be swapped to a heat pump later? Heat pumps run at around 45-50c flow? Thanks

 

[John.g]

Boilers only start to condense at ~ 50/55C, see below.

 

[Matt0029]

Boilers only start to condense at ~ 50/55C, see below.

Thanks I thought the idea was to make sure the return was coming back at this temperature not the flow. But then again I've know some new system to only have a 6c difference flow and return.

 

[ShaunCorbs]

Condensing boiler 55/35 dt is 25
Heat pump 47.5/42.5 dt is 25 that’s why so systems are heat pump ready

 

[Ric2013]

What about legionella protection for DHW?, will all new boilers now have to have HW priority and increase the flow temp to 80C?.

That would be good. Had a long discussion with a customer recently about what temperature she should set her boiler flow to and I mentioned that ideally, the boiler would do just that (but hers doesn't).

 

[Matt0029]

Condensing boiler 55/35 dt is 25
Heat pump 47.5/42.5 dt is 25 that’s why so systems are heat pump ready

Is it looking more so that heat pumps may take over. I know there was talk of hydrogen blend/ hydrogen.

 

[Matt0029]

I've never managed to get a 25c delta T. Have struggled to get 15. We can't adjust the pump in the boiler. So just lockshield? I think Vokera mentioned on one of there boilers they had a pump were you could set the delta T.

 

[Matt0029]

Also does it mention anything about aluminium radiators? Which there say to install for heat pumps.

 

[snowhead]

Conservation of fuel and power: Approved Document L

Building regulation in England setting standards for the energy performance of new and existing buildings.

www.gov.uk

 

[John.g]

I've never managed to get a 25c delta T. Have struggled to get 15. We can't adjust the pump in the boiler. So just lockshield? I think Vokera mentioned on one of there boilers they had a pump were you could set the delta T.

Vokera Unica Max I read somewhere and perhaps some version of Ariston??

 

[Matt0029]

Yes I have done a few of the Vokera webinars on an evening. There great for learning