Nickfromwales

If it’s sealed and pressurised then it would be periodic rather than frequent, but the risk of it being more problematic would be real. If you purge each loop one at a time it may push through, but that would be down to trial and error. If you’re putting an automatic bypass in ( so all rads can have TRV’s ) then fortify that with a gate valve so you can close that off 100% for future purging. You’ll need 100% of the pump flow to do the purge effectively, so you deffo don’t want the bypass operating whilst doing so. Closing the bypass / using it as isolation should be avoided.

My pleasure lol.

Dependant upon where your airtight layer is of course Pipe work shouldn’t be outside that really, even more so for heating primary’s.

No. You’ll just have AAV’s up high to deal with that. Do you still have to do a flat roof? Or will you have an attic / other accessible void above?

If the manifold has to go low then no, but if it can go much higher up the wall then yes. Honest answer is.... why not just drill holes through the wall? Or do the pipes run through attic / ceiling space and then down? This will work with a purge at the commissioning stage, but recurring air locks will be an issue over time.

Segregate potable ( drinking quality ) water system and bathing water systems from the get go and then go for a pressurised artificial cold mains created by 3x 500L cold mains accumulator vessels. Hot water cylinders or Sunamps can provide all the hot water you’ll need, and you want to aim for around 600L of stored hot water. That would be 2x 300L UVC’s or 3x size 9 Sunamps. UVC’s need annual G3 inspection but Sunamps do not. Cost is roughly x2 to go for Sunamps but the form factor is also beneficial as it’s a factor of about 3 compared to UVC’s ( Sunamps being smaller / compact / less complex ) so less space needed for the same capacity. Its down to how much space you have? What plant space is available? You can also go for gas instants, one per floor, for instant hot water, with something like a Rennai 50kW instant gas multipoint. Cold mains will be the killer here as no cold in = no hot water out, regardless of what provides hot water Whos paying the gas / electric bills?

You can purge each run, one at a time, with cold mains to get rid of all the air, but even with inhibitor air ( gas given off by the rads slowly corroding ) will collect at the high point and eventually cause another airlock. Putting AAV’s at the high point is an option, or T’s with drop pipes and manual vent caps will also work ( if you cannot go any higher than the high point ). The CH pump on / prior to the manifold will not push the air through if it’s a full floor height of head up and back down again. ?

@AnonymousBosch I see 900mm as one dimension, what size wet area are you allowing? 900x900 is a very small area if you aren’t intending on fitting a screen / cubicle of any sort. As far as your other woes, I don’t really see this being much of an issue unless there’s something I’m missing..... Diamond Wetrooms do a reasonably priced 900x900 wetroom former which is cheap enough, and GRP so no issue with mosaic ( Wedi products can compress when applying point pressure on small mosaic ) and require little in the way of accuracy of the underlying works as you can bond them down into wet adhesive to set them level prior to fixing down firmly with mechanical fixings. I’d recommend a 1200mm or 1500mm area if you’re going to all this effort. £258 for that 1250 square. Hire a concrete grinder to remove 30mm of existing floor area to accept the perimeter of the tray and happy days. “You can do it, Deeds” ?

Yes, as long as ring beams are observed at those points. Studs get stacked in multiples where they support a steel, and the timber transfers the load to the slab. Commonplace in TF structures.

Should also read “visible” as compression on gas is less than preferable.

@PeterW Can you skim over FC as is?

@Visti @Russdl The router will be your friend. On the downstairs ceilings, when affixing to the underside of the pozijoists, please do yourselves a huge favour and router 3-5 mm squares out of the back of the FC boards where the joists hangers are God ( please select as applicable ) help you if you don’t, as sanding back the jumps / humps / bumps on the ceilings where these rigid unforgiving boards have been used, will be a bitch. Best of British chaps, @Russdl, Chuck those screws in the bin mate FFS !!! If they have no purchase in the resilient bars you’ll end up with cracks and a life of filling and painting ?.

He does come from a rough area.....?

Skirting tiles.

25 years for me so you get grandfather rights over me lol ?. When you stand in a bathroom and look directly down the wall to the floor, on one of my tiling jobs, all you see is tile. The grout line that’s left when you tile the floor afterwards, and I have had to do it that way a few times, isn’t acceptable to my OCD, plus under grouting ( under the last cut wall tile ) vs grouting the gap between the cut floor tile and the existing bottom wall tile isn’t cricket. If you silicone over that on one of my jobs.....you’d be sacked on the spot too ??. My bathrooms are as near to ‘silicone free’ as I can get them. Hate the stuff. A lot of the tiles these days can be bought to compliment wall - floor junctions. So if the grout lines are to go down one wall / through the floor / back up the opposite wall, on both the parallel and perpendicular grout lines then tiling the floor first is absolutely the only option. Antinox or 4mm plywood will give ample floor protection.

A TS with a 22mm DHW coil gives LOTS of DHW flow, but I have gone to 28mm when combined with either an accumulator or a damn good cold mains. I have only ever fitted coil types so have no experience of TiT versions sorry. Can’t say I like the idea though as the heat transfer rate in the coil version is excellent, whereas a) the TiT version probably needs time to recover and b) it’s only 80L......

Maybe. But..... I wouldn’t fit multi panel as it’s a ticking time bomb. I did a whole house ( all bathrooms ) for an Ebuild member and indeed tiled the floors / fitted shower trays first, then scribed the Mermaid panels with a router, and dropped the bottoms of the panels into a 1/2” bead of clear CT1. The excess that displaced after pushing the panels down and home was removed by wet wipes and CT1 Multi Solve spray and I’ll bet my left testicle that they’ll be watertight until I snuff it. Jobs as good as you make it ?

KISS

Not on my shift mate ?. Always floor first and then tile up and away. The only time I break that rule is if it’s mosaic in a specific area and I’ll then size the opening to take full sheets of mosaic. If you’ve tanked and sealed properly you don’t have to panic about that detail. It is preferable but not life or death. I’ve done enough “grief free” wetrooms to know ? A true Wetroom install should be OK to use WITHOUT EVER TILING IT, remember that and you’ll be fine. ?

Put the gmail app on and just use that directly ( is what I do ).

TRV’s don’t need to be “smart” just £10 a pop and you’re cooking on gas ? There are open source intelligent / smart options available, and IIRC @DamonHD has such a system available. Send him a PM for details. I’d try that option first VS the buffer chop & change and see if the cycling reduces enough to not be problematic. One towel rad could make all the difference as you can include the volume in all the connective pipe work too.

As you’re looking to be buffering kWh’s of heat and not looking to add volume per se, then you really would benefit from a sizeable buffer tank, eg minimum 100L but preferably 200L tbh. A super insulated vessel is recommended unless it can be sited to utilise the waste ( latent ) heat loss beneficially eg in an airing cupboard or strategically positioned on the ground floor to contribute to local heat requirements. A low loss header will do very little to improve things as they’re normally utilised to attain hydraulic separation ( vs a dedicated buffer ). Your best bet would be to have the radiator zone valve always open whenever UFH is selected, and have one strategic radiator on manual valves as a bypass / heat loss radiator. You would again need to have that allocated where it would be advantageous / not a nuisance ( airing cupboard or bathroom towel rad(s) for eg ). The boiler will quickly heat up a small buffer, and then you’re back into the flames from the frying pan.

The Gledhill provides your DHW though, so it’s a thermal store not a buffer, it just buffers as a by-product

You can’t if it’s a combi I as it’ll need it’s full kW rating to produce DHW Producing heating actually requires a much smaller energy input vs firing up to produce DHW. That’s a 40kW high-flow ( that refers to hot water production not heating ) combi do you cannot do anything to reduce its max output capability or it’ll give warm not hot water.

Is the suction side fed from a dip-pipe? If the water level gets low enough when the pump is at full wallop there is a risk of sucking in air and water not just water. Even so, if the pump is at the source then this should not be problematic as water will eventually get through. Is the pump ‘man enough’? FYI Air admittance valves AAV’s will let air in as well as out, so could add to your problems instead of curing them.