PeterW

The chassis has three things swapped usually - heat exchanger, gas valve and system board (or firmware) That is how you get more gas into a bigger burner and then into the water. Some also change the burner assembly for one with more rails but that is less common.

So the water is a closed system and the temperatures are so low you wouldn’t get precipitation anyway - an inhibitor also changes the pH so tbh it seems a lot of effort for nothing and I’ve never seen a UFH system with issues from deposits - it’s usually galvanic corrosion from different metals that causes the problems so a filter and inhibitor is your best bet.

Boiler cycling on oil is not good - not sure how clued up your architect would be on this, but the plumber should know better..! And what are you filtering...?? A full UFH system holds 80-150 litres of water at most depending on the loops - you fill it from mains pressure clean cold water, and add inhibitor. A decent mag filter is less than £75 and will keep all the crud and crap from building up anyway .

Most of the big power flush units do upward of this - they really do give the system a good high flow flush to get the crud from radiators and pipework. The downside is a lot of modern boiler heat exchangers have very fine galleries and they can block if you're not careful.

@AnonymousBosch that is the same image that was in the bathroom of our villa in Italy two weeks ago !! @vivienz the issue is that MVHR is a commercial product that is just catching up with the domestic market. Commercial customers tend not to want "unobtrusive" or "pretty" as essentially its a component of an essential M&E system. The closest I have come are the Starline grilles but as you are never viewing it face on, but rather side on, it is an expensive solution to a problem that potentially doesn't exist - you do tend to ignore the vents after a while.

Power flush units are pretty powerful - 100 litres a minute is not unusual for the pumps.

As @Declan52 says, the blender is set to 35c so the ASHP CoP is better.

Not really as BG will get to a point of charging you £2200 for a new boiler at some point. So that’s a TCO value at £360 p/a inc write off. Yours is £350 p/a plus additional boiler so would be £650 p/a...

But rads don’t fail like they used to anymore. The biggest issue is rust and crap in the system and old header tanks used to be the big cause of that as oxygenated water gets in. Fit decent rads in the first place, don’t use B&Q specials. Then decent levels of inhibitor and a good mag filter, preferably with a strainer too. Plastic pipe also helps as there is less corrosion / galvanic action with less copper in the system. These filters are pretty good and not expensive. Also have a stainless gauze in them to trap bits of non-magnetic crud. And pick a boiler with a stainless heat exchanger with a decent warranty and you should have no problems.

Mine has one - called the Mag Filter. Can empty it, then it takes 500ml bottles of inhibitor.

Last one commissioned was a full slab install with reasonable levels of insulation (not Passive) and good airtightness and it’s purely on E7 and ASHP. DHW from 01:30 to 03:30 at 47c UFH from 04:00 to 07:00 at 35c and room stat at 20.5c Both get a boost from 18:00 to 19:00 and 19:00-20:00 respectively if needed. 300 litre DHW tank gets boosted from 47c to 63c by E7 from 05:30 to 07:00 to give a lot of hot water.

Haven’t seen a gas boiler suitable for external mounting. There are boilerhouse models, but most if not all need to be somewhere above 5c at all times.

Ahhh then don’t box it in, don’t stick it in a corner and make sure there is 300mm clear all round.

1. A magnetic filter / cleaner is a requirement on most if not all new boilers 2. Pointless - use the drain on the mag filter (see 1) 3. You do anyway. 4. Pumps are fitted with valves. Adding 3 full bore valves around a diverter would be different ... 5. It’s there already - use a drain point valve on the utility radiator/ lowest rad. System already should have a filling loop to refill. 6. Nothing. Nada. Nowt. It’s illegal, don’t go there.

No, but if it failed and caused significant injury, or damage to property, the insurer may not pay out. This is also the risk with unvented cylinders.

Fit an ASHP... job done ...

Meter installation is free - just ask for a new connection.

So the only way is sign up with one of the Big 6 on a standard variable rate tariff with no exit fees, get the meter installed then immediately change suppliers once you have your MPAN It takes 2-4 weeks to switch and to be honest it will be pennies different on the rates, the standing charge will be your biggest cost.

So that assumes it’s not a system boiler where the expansion vessel requires repressurising then ..? Or the FGA values checking to ensure the mix isn’t out due to needle wear in the metering head... or the CO level isn’t off the scale due to blockage in the inlet air vents ... Circ pumps run much better in clean water with less crud in them, and gas valves fail due to the fact most are metering valves that move constantly based on gas pressure and heat demand ... servicing is no bad thing !!

Don’t forget that self levelling compound is not designed to be a wearing surface according to the manufacturers and if you need that then it’s probably an epoxy / concrete based system that you need.

That will need a VCL to make sure you don’t get problems. You could lose the first OSB in the middle, and just screw the top board through the PIR.

90% of those aren’t just for foundations though...?? Total cost per square metre excluding plot is probably still the best measure.

140mm stud with full filled PIR, 15mm OSB and 25mm cavity will out perform a 100/100/100 standard build that will still need the same 37.5mm insulated plasterboard and will come in much better thermally and from an increased air tightness.

I have all the straw bale books I could lay my hands on as I really considered this a few years ago. I remember seeing the GD though where they used them internally and thinking I was happy I hadn’t ..!!

Lovely typo in the Bosch website .... should be 0.025 degrees ..!! So more acceptable ..!