Nickfromwales

I had exactly the same issue(s) with a Worcester Bosch boiler serviced via a British Gas ‘insurance plan’. BG came out, 5 engineers over 4 visits, fault not cured, and basically rebuilt the boiler in situ from bottom to top. Left the box of spares in the utility room as a trophy, to demonstrate how they’d done “everything possible” and they then left with the client having no heating or DHW. Told him he needed a new boiler and said they’d post a quote. I went there, and 45 mins later I had the boiler working perfectly. Client was sooooo pissed off he rang the area manager ( the 5th chap you accompanied the final service engineer ) and gave the phone to me. The guy asked me what I did to fix it and I told him to keep guessing. So fed up of visiting customers ( pensioners mainly ) who have been a victim of this tactic from BG. I had to threaten them as a company to come and rectify a list of faults, one which was lethal, and gave them an hour to respond before I called the GSR to report them. After a load of condescending threatening waffle, 40 mins or so later 2 BG vans materialised. They told these pensioners that they needed new controls and the £5k glow worm boiler ( £600 in my plumbers merchant btw ) they just fitted ( in a day ) had to be left off indefinitely. I was contacted by the electrical firm that BG eventually appointed to try and fix it, 3 days after leaving an immediately unsafe installation and an 82 & 83 year old without heating or hot water, and I couldn’t believe how bad a job they’d done. All they had to do was wire a modern system boiler to a standard S plan system. Ffs. All these “heating engineers” these days are just plug n play laptop jockeys who cannot think outside the box. Get them back into proper apprenticeships!!!!

That means the diverter valve is not parking in the fully closed position. Most diverters park in the heating position, and then move to DHW position swapping duties 100%. The diverters park in the heating position to do pump overrun, the heat dump cycle after each burner ignition event. Yours is not getting 100% of the way closed aka diverted, therefore you have the heat leak to the rads. I have to be honest, you need to remove this and get a full refund. Go grab yourself a Vaillant and get on with your life. Intergas and Veissmann do some strange choppy-changy is it a system boiler or is it now a combi nonsense and I’m not a fan at all. You’ve done the polite customer to the extreme, now you just need to contact them in their UK offices and ask for the unit to be removed and draw a line under it. Can you imagine sorting this and then going to the same bunch of clueless halfwits for the next problem ?!? Time to call it a day I think, before winter when you really need it to work reliably.

A lot of UFH gets installed badly, so the comments from your plumbers don’t reflect well on them I’m afraid They should have told you what you need to do to have a successful UFH installation, not just spout negatives! Have you bought the combi yet? If not, buy a system boiler instead and run a thermal store ( 180-210L ) and get bags of hot water from that, way more than from a combi too. The TS will also provide a pair(s) of tappings for the lower grade heat you need to feed the UFH with. The mention of a store is because of the oil boiler, because oil burners cannot modulate ( go to a small flame for low output like a gas boiler can ) so you get 0-100-0% “all or nothing” output which needs to be captured over a long ( economical ) burn, and then drawn down via the store. The downside of the TS is it needs to be hot pretty much 24/7 to provide hot water on demand, but the difference in hot water supply will be huge vs a combi. Bottom line is, you’ll need a buffer tank or TS, particularly with retrofit UFH. Draught proofing the house, 3G doors and windows, and insulating as well as you can will reduce the amount of heat you need for the house to stay at 21oC, so UFH can and will work we’ll if you don’t fail to prepare. Get new plumbers too. ?

Chipping away at that clay pipe will likely just see it disintegrate, so you’ll probably need to dig it out, cut it clean with a grinder, and reconnect with a rubber clay > PVC union. You then take new PVC pipe into the chamber and connect with an offset 15 or 30 degree bend going into a long radius bend if you have room for it.

?. Bypass normally only allows the pump to recirculate back to itself via the return, so the pump needs to be going before the bypass could ever be an issue. The pump should not be running if there’s no call for heat, so I am dubious about that being a solution tbh. Stunk of diverted valve issues, but you say that’s been replaced? Most combi boilets go into pump overrun after DHW has been drawn, to get rid of the nuisance heat, the high temp heat left in the primary heat exchanger, and that goes to the heating circuit but without a flame. Eg the boiler sucks cool or cold water from the central heating into the HEx to cool itself down for between 1 and 2 mins typically. Then the pump should shut off. Ok; PS. Wow! You are the most patient person I’ve ever heard of. By now it would have been off the wall and dropped off at the point of purchase with “return to sender” written on it in permanent marker.

As ever, we digress. ? On a recent Velox ICF build I recommended a full internal cementitious parge coat, to turn PP the reveals, and to then tape between the PP and the window / door frames.

That depends upon what you’re sticking the membrane to and where that next stops. The MBC ph PIR + rockwool system does exactly that, but the entire dwelling interior is an airtight membrane so kind of cheats out the question of windows / door junctions. Traditional membranes need mechanical fixing, liquid membranes ( like the green paint on AT OSB ) need a substantial substrate to be applied to. All changes with whichever differing construction method is used tbh.

Incorrect. Smart ply on a TF gives you window > AT junction. Just needs tape to finish.

It is with Velox I’m afraid, as the window and door reveals are bridges to outside atmosphere so need a fair amount of detailing to mitigate, also. To be clear, airtightness is paramount with ph levels of build fabrics, and some systems offer ‘reasonably good’ AT standards without adding to the mix. 0.26, 0.27 and 0.28 on builds over recently been involved in are exceptional scores, but beating ( halving ) the shitty standards set out by IK BRegs is still easily achievable with these off the shelf ICF systems. Knowledge is important, as some minor tweaks and a few quid spent strategically can see you get much better results, if that’s what you wish to attain.

Depends on whether we have one leaky gas joint or a few........ Neighbour called me to say they couldn't light the gas fire any more. I went into the alleyway dividing the two terraced houses and removed the soot plate to find that rainwater had been dripping onto the copper sleeve of the 8mm gas pipe for years, and it had eventually got through the sleeve and had made a hole in the 8mm pipe, worsening year by year. When I got to it, the gas was following the convection airflow from the living room, up the chimney to atmosphere at a rate of knots. As they were pensioners on a fixed costs tariff, they never got alerted to the huge amount of gas leaving the pipe and whooshing up the chimney for what must have been years!! Christ only knows how they never smelt the gas when the wind changed direction, but the house was at a constant 25oC, as they were freezers, and the convection out of the living room up the chimney was like a hurricane.

Agreed. It can be mummified in dense rockwool and the losses nigh-on lost. Or a PIR box etc.

Not me guv'. Remember I am a fan of boilers in attics, where space is constrained, and I've put many an UVC in an attic, again for the same reasons. If I was asked ""is that the best place?", I would have always replied "nope" followed by "it is what it is".... If there is somewhere within the heated envelope for this stuff, then that is where it always goes.

As the attic cools down the delta will rise and the losses will increase. 50L can suffice if the system is not too small. Remember that the buffer can be installed as an energy buffer rather than an intermediate heat bank, so basically it becomes an energy balloon, inflated an deflated in line with downstream heat demand fluctuations. When the call for heat goes off, the buffer no longer gets serviced ( heated ). Use of single check ( swing check ) non return aka anti-gravity valves will ( can ) reduce heat convection away from the buffer during the 'cool' cycles of any heating cycle.

Plus all the interconnecting pipework / connections etc. Any waste into a cold attic is bonkers. No constructive maths will change that.

As always, it's down to the OP to give advice on mileage / frequency etc. I'm pre-programmed for the larger mileage I suppose, as I do over 40k a year between the car and the van

Eh? Octopus Go! gives 5p/kWh between 00:30 and 04:30 so I can definitely see why you'd want to charge both cars at the same time on rapid charge thus maxing out one whole phase pretty much. That's great for general charging if you don't have PV, or for giving the home priority if you do, but don't have a 'huge' array. Cars are a good place to store excess PV but it's far too much to expect PV to charge 2 vehicles fully all week long for on-demand driving.

The most important and most difficult to detail area is at the lower outer edge of the roof where it forms the eave / soffit. On garage conversions where we typically have to retro insulate, just as you need to there, I found it SO much easier to get a sheet of 200mm rigid PIR ( kingspan / cellotex etc ) and make ~600mm x400mm blocks which I then cut in half diagonally ( to form wedges which match the pitch of the roof ) and to push fit them into those awkward spaces and foam for rigidity to keep the minimum 25mm air gap. Remember to cut them short, eg lose the thin tapered bit of the wedge by cutting it off, so they only project as far as the ventilated cavity. That ensures good airflow is still free flowing up the cavity and into the space above the soffit and up to the ventilated ( cold ) roof space. Worked a treat and completely mitigated against the risks of rock wool touching the roof / felt and causing condensation / bridging damp etc. A pig of an area to detail with wool. I then fit 2-300mm of rock wool up tight to the PIR where it has a nice uniform edge to abut with. running horizontally across the ceiling to meet the same detail the other side. The PIR on the walls can be taped to the PIR at the eave junction also then, giving a very robust joint detail where the wall meets the ceiling

That can cause huge problems with balancing a larger system. All of the pump potential looks to escape through the towel rads before servicing the furthest away / most difficult to ‘get to’ rads. It would also slow down the rate of recovery ( how long it takes to reheat a tank full of hot water ) significantly. I would not recommend doing that at all if it’s a larger system / family home.

You do NOT want the ASHP firing up just to warm some towels!! That would be hugely inefficient and would cause all sorts of problems with short cycling. ?. Put the towel rads on dual fuel elements so they come on with the ASHP any time it’s running heating ( which will help out with smoother running of the ASHP whilst servicing the UFH ) and just bite the bullet on a bit of direct electricity for the summer. Do you have PV in the picture?

Select 50L model This will suffice if you have 2 floors of UFH. Dimensions are there, and these wall mount and are very well insulated.

Heat source to buffer requires a pump. Buffer to UFH primary pipework requires a pump. Each manifold requires its own pump also. You will have 4 pumps

You wont need 3 phase unless you plan a huge PV array. You will need a second phase for the 2x car charging points ONLY and that's it. Run a 4 core cable, get a 3ph meter installed, and just pick up L2 for an outbuilding / garage, eg preferably where the 2 cars would be parked / charged.

Ok. So, things like insulating the loft as much as you can, foaming around pipes etc or any places where an unwanted draught are present, and sealing around the perimeter of the floors ( heated or not ) will reduce the ventilation heat loss. In terms of insulation, how much have you space for? Type? Aluminium spreader plates are quite good diffusers, but only work really well if in contact with the decking ( floorboards in your case ) so make sure you get some mineral wool insulation under the plates so they are distended upwards by around 10-15mm so when the deck gets screwed down they are under compression. I would recommend triple groove plates so there are 3 runs of pipe per joist space, and they provide iirc ~120mm pipe centres. This will give far better ( greater ) system volume and a much more robust heating distribution, but as a bungalow I fear you will not get way without at least a 50L buffer tank to help when the house is nearly up to temp but still pulling heat, just very small amounts will be needed at that point and the boiler ( or future ASHP ) will inevitably short cycle during those events.

Hi. It all depends on the heat requirement of the spaces you plan to install heating into, and therefore how hot you have to run the UFH flow temp to get x W/m2. UFH is not a fit and flick the switch on solution, and needs a LOT of thought before even considering as an option. Is the space a cold ventilated ground floor, or 1st floor? How do you intend supporting the pipe? Have you considered any makes / types / methods yet? Heat source?

Neither most likely. They're both "newly adopted" build techniques are they not?