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Discuss Bldg regs compliance / Interlock in the Central Heating Forum area at

  1. Luke78

    Luke78 GSR

    Hi all...

    Relative newcomer to trade and doing this between other (unrelated) employments so forgive me if following questions identify me as a little "green".

    A customer has asked me to look at their boiler/central heating in my capacity as a GSR engineer.
    The customer had a visit from Gas Safe earlier this year following a gas leak from their gas fire which had been "decomissioned" by a 'qualified' relative who turned out not to be.

    I can handle the gas issues without difficulty but the GS inspector's report also highlighted some building regs contraventions which were not directly within the Gas Safe remit.

    These include no boiler interlock, benchmark only part completed and install not notified to local building control.

    So... my questions:

    As the installation has not been notified to buliding control, but I believe it pre-dates recent changes to building regs, must I make it compliant to present standards before I can notify it?
    For new appliances I usually do this via the Gas Safe website (for £2.00 -odd or whatever it is presently).

    If yes...

    If I follow the full comissioning procedure in the boiler manual, even though it is no longer brand new, does it still qualify as comissioning and can the benchmark cert be completed to achieve compliance with current regs?

    The report highlights the absence of a boiler interlock in the system and the inspector suggests that converting the radiator in the same room as the thermostat from having a TRV to an ordinary lockshield valve would satisy the requirement.

    Is this correct?

    As explained elsewhere my primary experience thus far has been on gas elements of installations so, again apologies for any apparently daft questions.

    I remember receiving a very helpful email with links to a guide to complying with updated building regs on interlocks etc, but, frustratingly, can't seem to find it now it would be useful... Even links to any general data would be well received.

    Thanks for reading!
  2. scott_d

    scott_d Plumber GSR Top Contributor!!

    I wouldn't notify someone else's work
    Especially if it's poorly done as you describe.
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    • Agree Agree x 1
  3. Luke78

    Luke78 GSR

    Take your point, Scott, and it makes sense but would still be interested to know how the matter stands? Think I can put right the rest of the defects and get the installation compliant, just not sure about how to achieve the interlock part...
  4. AWheating

    AWheating Trusted Plumber GSR

    interlock is timed and temp controls that control the boiler. so a room stat and time clock possibly with zone valves dependant on what the system is. Basically the standard controls you would always need to fit to meet the regs. This has been required for many many years not just since the building control certification stuff.
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    • Agree Agree x 1
  5. chris watkins

    chris watkins Plumber

    As above,
    but it can also be met in other ways now, basically the requirement to "interlock" the boiler is used in the Domestic Heating Compliance Guide (search to find & download the pdf.) to mean a mechanism which will stop the boiler from firing when there is no demand from either heating or hot water e.g. a system with no room stat installed but rads are fitted with TRV's is not compliant under Part L Building Regs because although they will provide temp control in each room there is no signal back to the boiler to turn off when the house gets up to temperature. The Boiler would "cycle", turning on & off just keeping pipe work hot which is wasteful.
    A TRV should not be installed on the rad (normally the hall) in the same room as the room stat as there would be a conflict between the two, just a normal w/head & L/shield valve set required.

    What is the system & boiler Luke?
  6. Luke78

    Luke78 GSR

    Thanks for replies everyone-

    AWheating: I had a feeling that the interlock requirement was not terribly recent; I guess what I was (not very clearly) saying was that, in the wake of the more recent changes, there have been various guides appearing online and in trade publications etc and I remember reading one which mentioned the interlock requirement and how to satisfy it, and had me thinking "Ahhhh! so *that's* what that means..." :rolleyes:

    Chris Watkins: Thanks for your brilliant plain English description!
    The system is pretty straightforward: Baxi duotec 24kW combination boiler with a RF programmer/thermostat unit.
    Complication is that the client doesn't have the programmer attached to the wall, meaning it could potentially be carried around the house... The room where it seems to live usually (kitchen) doesn't have a radiator in it, although there is a radiator in the adjacent hallway and no door on the kitchen.

    Am guessing the simplest way to comply would be to persuade the customer to have the programmer attached to the wall and to remove the TRV from the nearest radiator... Not sure they will agree, of course...

    Indeed, in that vein, there are a couple of other issues that the Gas Safe inspector's report highlighted which relate to building regs and have been classifed "Not To Current Standards" / "Not Compliant With Building Regulatons" and appended thus:
    - I have a feeling the customer will be reluctant to have me undertake some of them as it will cost them for my time and they will see no apparent difference. E.g. benchmark completion, Building Control notification (which, of course, is a catch 22 because I would be putting myself in a tricky position as I can't technically notify unless the installation is compliant!),

    So, in anticipation of a refusal by the customer:
    Would I be fulifilling my professional obligations if I were to concentrate on rectifying the safety critical defects (those classified "At Risk": which are gas fire flueing defects and pressure drop of greater than 1mb from meter to boiler) and for the rest of the points, gave advice -in writing to ensure it was on record- that there ARE still elements of the installation that contravene Builidng Regs, but the customer declined to accept the advice?
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  7. chris watkins

    chris watkins Plumber

    In sort yes.
    How old is the boiler ?
    On the controls side I would advice the customer that for the system to work at intended it should be fixed to the wall, as normal, in the hall & the kitchen is not the best location as it is likely to be effected by other heat sources but at the end of the day it is their choice. The installer provide time & temperature control over the boiler in the form of a programable room stat. They can't be held responsible for how it is used.

    I think the people who write these reports are obliged to point out any problems they see even if it is not strictly in there remit or even correctable.

    In that vain, did the inspection state the amount of drop on the gas or did you check what it was?
    A lot of boiler manufacture allow more than the 1mbar at the boiler but you would need to check the M.I's.

    If the boiler more than a couple of years old I would advice them not to worry about the fact that it has not been notified via Gas Safe to BC, the sad fact is it is unlikely to be an issue until the house is sold, when it will picked up & then dealt with by the buying (seller) of an indemnity insurance policy to protect the buyer.
  8. Vee

    Vee Plumber GSR

  9. chris watkins

    chris watkins Plumber

  10. Vee

    Vee Plumber GSR

    If he is notifying it then he is exactly doing what he shouldn’t. The notification should be made by the person who installed it and not retrospectively. He is putting himself in jeopardy. Otherwise you are also helping to keep the cowboys in business, as they know that if they can find a mug to correct and sign it off, they can carry on installing. I am not saying he shouldn’t correct the work.
  11. Luke78

    Luke78 GSR

    You understand perfectly, Chris.

    I have no intention of "signing off" another persons work; I simply want to be clear about exactly what I need to do to leave the customer with a safe and compliant installation.

    It seems from posts above that I can fulfil my professional responsibilities without notifying the installation to building control and, -for the very reasons stated and UNDERLINED by Vee- that is something I would prefer to avoid.

    I have been called to a property with 2 appliances that have been turned off and classified "At Risk", and asked by the customer to -if possible- correct the faults and recommission the appliances.

    I just want to be clear that if I do that (assuming, as stated above, it is possible) and ONLY that, but do not address the "non Gas-Safe" related defects, that I am not leaving myself open to charges of incompetence or penalties in the event of a future inspection...
  12. Luke78

    Luke78 GSR

    Seems our posts crossed there, Vee!
    So... Correct the defects, but don't notify to building control as that is the previous "engineer's" responsibility.
  13. Vee

    Vee Plumber GSR

    Yes. Absolutely. Correct defects, but no notification to Building Control. If there is refusal to correct gas safety issues, make sure to get a notice signed by customer. Hopefully they are sensible enough to get the pipework issue addressed.
  14. Luke78

    Luke78 GSR

    Thanks Vee!

    I also see reading back that I didn't answer this point:

    The inspector's report reads: "...inlet working pressure of 17 mbar was recorded at the inlet test point on the Baxi boiler... and operating pressure of 19.76 mbar was recorded at the gas meter".

    On the day I visited I tested pressure with boiler in service mode and water gauges connected at the meter and boiler simultaneously; results I got were 20mb at the meter and 18.75mb at the boiler, which is a significantly lower drop than the inspector found, but still exceeds 1 mb.

    Take your point re: manufacturer's tolerances but I guess the only way to build a better picture would be to check working pressures at the meter and other appliances in the house (cooker, gas fire); which I have not yet had the opportunity to do.

    Concern is that the customer has recently had a new kitchen fitted and is proving reluctant to let me pull the back out of all of the cupboards to trace the route of the incoming gas pipe! I will continue to press the issue, of course, but if they ultimately refuse, I guess my only option is to turn the supply off and classify the installation "At Risk". Which leaves them back at square one!