sharpener

12kW Vaillant is almost imperceptible from the side and not very noticeable from the front unless putting out 10kW or more which is rare. Sucks from back (only 200mm rear clearance, 250 if for cooling) and blows v cold air out from the front. Visitors (who have to walk past it) have remarked on the cold rather than the noise.

I think you have probably found the solution. IIRC Farnell stocked the right one for me but I didn't want to buy one as a spare for precisely that reason. Steca would not confirm it but the loss of time and date following power interruptions led me to the same conclusion. I think the first replacement inverter may have been old stock as the model had been superseded.

IME they all pad the quotes with an unquantifiable amount for "MCS compliance costs" or some such which means some scope to haggle. Tell them you would like to give them the work, what can they do for you? "Nothing for the dumb" as my mother used to say. Various horror stories about BG on Vaillant forum, I would steer clear of them.

Like my 2011 Steca solar inverter it might have a supercapacitor for backup, 3V Panasonic IIRC. Not very reliable, have had whole inverter replaced twice under warranty bc it failed, will try and fix it myself it it goes again as is now out of warranty.

S Devon. I think your quotes are pretty high for 7kW, unless London/SE. Try asking the HG if they can match the BG one or come near it.

Entirely, the problem might be in forcing the HP to run at that low output. Noise Reduction mode could be the solution.

Yes. Even years ago heating a conservatory outside the thermal envelope from yr central heating was not allowed under the BRs. You were supposed to fit electric UFH (which is of course more expensive to run and worse for CO2 emissions, makes no sense if you want the heat anyway). So got the plumbers to drill through the wall and fit isolating valves. After the BI had been to inspect the new utility and loo off the conservatory I fitted the rads myself and connected up. Separate zone for the Honeywell Evohome, TRVs set to 16C just in the morning to take the chill off.

Spot on. Our loft conversion firm "preferred" to use a private sector one. He said he would if necessary get them to open up their work to rectify missing ridge ventilation but in fact didn't. It was clear that he didn't want to jeopardise a lucrative, captive stream of work. However it dried up anyway as firm deservedly went bust, fortunately I had kept back £500 for reinforcing floor joists they had weakened with non-compliant holes for pipes. Nightmare.

BG will probably subcontract the job so it's anyones guess who will do it at what standard. Press them to tell you. Gledhill are reportedly not testing their cyls 100% and leaks and rattling internals have been mentioned somewhere. What size? FWIW I got a Vaillant 12kW HP, 270 l thermal store and 8 new rads for well under your BG quote.

It's annoying that Vaillant's Noise Reduction Mode only supports a limit in the restricted range from 40% to 60% modulation. I don't see why they could not make it programmable to choice. My experience with the 12kW is exactly the same, it is only noticeably noisy at the top 10% of the output range, so a limit of 90% would be ideal for a noise-sensitive location and only compromise performance at really extreme OATs. Have you tried the Current Limit feature as an alternative? Even if it is not that effective, telling yr neighbour that it is switched on might placate him.

If you search amongst @JamesPa's posts about a year ago there was a lot of discussion about various possible measures including commercially available enclosures (v expensive) and mats behind the HP. Also as you have found, the most objectionable noise only occurs in the top 10 - 15% or so of the power range. Is there any way of limiting the output power somewhat whilst still leaving enough to keep you warm, perhaps with slightly longer heating times? Might be labelled Current Limit or Noise Reduction Mode.

What is more relevant is that gas costs the same at any time of day! So there is no incentive to turn it off during peak periods which is when a concrete slab can usefully act as a storage heater.

You don't say what make it is. Vaillant installers seem to charge about £200 for the annual service, which is a condition of the warranty. As an alternative Vaillant themselves offer the service using their own field engineers for about the same price, reputedly they often discover setup issues which are costing you money left over from poor installs.

You will not get the thermal mass without the concrete. This means the system will be more responsive, but you will not be as able to bridge across peak electricity periods or charge the slab up only at night as IIRC @JohnMo does.

Thanks, that's what I thought but wanted to check here, spark who installed HP put n/k on his EIC. The BI wants another one for my DIY battery system and EV charger, have done them before elsewhere (am Chartered EE) so fingers crossed.