Nickfromwales

The supply and return flow rates need to be in as close to equilibrium as is practicable, otherwise the rate of air changes will not be optimised. If any hint of cooling is to be realised, this needs close examination and to be executed robustly. Elevated flow rates associated with 'cooling' or 'heating' bring with them a few bugs also, as in the audibility of the system when operating will be higher than that of domestic MVHR. For this type of install I usually fit 2x 92mm ducts to 2 separate air valves for supply, and then the same for return, with the cooled air at ceiling height and the return as low as is practicable. This promotes quieter operation and equilibrium in the room, which in turn preserves normal function of the MVHR system which would be running in the same room in parallel ( and must stay in balance as per its condition when commissioned ). The fan that provides air flow for this cooling should be room sealed to these ducts, both on the supply side and the return side to make sure the MVHR balance isn't compromised.

"If I could just say a few words..........."

Yes, my thoughts too. The principal bedroom is intended ( later in life when the stairs become an issue ) to be the downstairs bedroom, but we can ‘define’ that now for the purposes of getting signed off…..or so you’d think. Getting feedback from the BCO and designer that the upstairs bathroom “under the new regs” needs to have the 750mm opening. I’m yet to find out about these new regs ?. 1 bathroom downstairs which you can get a wheelchair to, plus the cloakroom, and still they want to carry a wheelchair bound person up the two 1/2 flights of stairs, turning 180 degrees half way up, put them back in their chair, and then wheel them into the upstairs bathroom. Curiouser, and curiouser…….

This seems as good a place as any to ask this question; On a new build atm, with level access etc, wheelchair friendly downstairs WC ( cloakroom ) and also a ground floor en-suite which is deemed as wheelchair accessible by the BCO. Downstairs en-suite is shower / basin / WC only, no bath. Q1: If this was the only means of bathing in this new build, would it satisfy disabled ( class II ? ) requirements in this, the year of 2021 ( England ), eg would there be a requirement to get a wheelchair bound visitor to a bath? There is in this dwelling an upstairs master bathroom also, which has a bath, separate shower, basin and WC. BCO is asking for a 33” door to be installed ( nearest size to the the 750mm across the opening that the door supplier can provide ) which I felt was creating unnecessary work ( there is a 27” door there atm to free up space ). Surely the upstairs bathroom can be deemed ancillary if the downstairs en-suite is “accessible”? Q2: If the dwelling has not been asked to comply to full Doc M, eg no considerations to independent unassisted disabled residence ergo has not been built to receive somebody who is single and wheelchair bound, then which level of classification should it strive to comply with? I cannot see why the upstairs bathroom would need the 750mm requirement if the dwelling already offers accessible ( assisted ) bathing and toilet facilities on the ground floor. Can anyone offer an educated opinion please! TIA.

The call for heat from the UFH will energise the cylinder stat on the buffer. That will tell the boiler to fire upon demand only. During the summer the buffer will remain cold. S plan is 100% needed.

An WB agent will refuse to go up there without boarding. Such a good ( aka expensive ) plumber would know this. Tell them to finish the job eg flooring from attic hatch to boiler area and insulate all the pipes. End of issue then afaic, and as you accepted the price you cannot dwell on it. Time to just move on to the next things and start monitoring costs before nodding your head

It depends on how much pipework had to be extended tbh. Couple of hundred to do the vertical flue, few hundred on pipe and fittings. Extended cabling for power and controls etc. A day and a half work at most for 2 guys. Tbh, I wouldn’t have done that for less than £1500-£1600 but would have included boards, lighting and insulation. Just noticed the boiler isn’t on a non combustible board. If it’s a Greenstar then it’s not a problem as they allow direct mounting on a combustible board like plywood.

The actual requirements for lighting / boarding AND a FIXED access ladder are only if it’s a boiler which is under the manufactures warranty. It is only to get them up there to undertake a repair, as they are governed by HSE and company employee liabilities etc hence they want a safe, well lit area with a FIXED attic / access ladder. If you use a regular plumber and you’re out of manufacturers warranty then it’s not mandatory, however, it would be a courtesy that I suggest you afford any poor individual who had to bend over / under / around that appliance to service / repair it. Laying in stinking dusty loft insulation in the peak of summer is about as appealing as…… you catch my drift. Fit some boards, a light is optional as a lead light would / should be in the van of any reputable plumber, and a fixed attic ladder is good for everyone. Any decent plumber would be well within their rights to refuse to work up there as it is. Also, tell the plumber to fit some pipe Insulaton ffs, it’s a bloody cold attic space !! Shit standards there, especially the condensate pipe. That job is currently far from finished, but more importantly it should NOT have been switched back on without a full GSR certificate and records of all the relevant tests noted in it. If it currently has no new certification then it should not be on or left connected to the gas supply. There is NO exception to that rule. The second you set a gas burning appliance to work it becomes a potentially lethal device. Also you need a CO2 detector in the attic or immediately below on the landing.

Yup. You could tank a Weetabix and it would be watertight for life. I do go mad with the tanking and sealing up corners / junctions though.

Agreed, but it’s a factor in this thread that folk should be aware of.

Just remember you can’t get paid export without an MCS registered install.

Take some pics of where you can / want to connect and post them here.

Primo Duo is the norm for me if installing where the pipe is subterranean.

Good to remember that there are rectangular ducts available and reduced size ( 75mm and 50mm ) round ducts too. CVC Direct supplied me with 225mm x 25mm for a project where we managed to hide the equivalent of 92mm round duct in the 35mm service void of an MBC TF build. Not a single bit of boxing in anywhere. They do supply only + design, or supply and fit and, I use them in both capacities with exceptionally good results. Great team and a fantastic pre / after sales support service too. @luz624 Just read that it's for a flat here, so without plans to show rooms vs outside walls etc it's a little tricky to offer much more advice. Do you have plans you can upload?

Hi. Why not go for individual MVHR units per room? link

They look a lot like rebranded Sunamps? Same with Fisher Future Heat iirc.

If 2 9x2’s have been specified then I’d assume the SE has detailed for them to be mechanically connected to one another along the centre point. Pozi’s won’t allow for that type of connection, so I’d say glulam or joists for this purpose but not Pozi / I joist etc.

Yup. They’ve done more like that than I’ve had ‘lamb dinners’

I am the principal M&E coordinator on that project, so the system is being installed to my spec / guidance. MBC have many of these under their belts, and they work fine for heating / cooling etc ‘out of the box’, and typically go in at 200mm centres in a serpentine layout unless someone specified differently ( for a reason ). Deviation of course causes uplift in prices For this project I am using very particular equipment, and also integrating cooling via slab + MVHR, so have done calcs which are unique to this sizeable ( 400m2 ) dwelling. One size does not fit all, so please do not focus too much on this detail for your build as it may not be relevant.

How are you heating yours? ASHP?

Yes, exactly why I’m doing it !!

The 3D cubes can be chopped and made to work, but second solution is far simpler of course.

Crossed with my reply. That’s the ticket !! ??

Surely that picks apart and you can create the corner with the parts? Remove the border pieces and construct with the square. Prob needs a Dremel / other to break the squares ‘apart’.

I’ve never laid serpentine in any of my installations. Reverse / inverted is the best layout afaic and allows for much better heat dispersion and almost zero 180o ‘U’-turns, which are not great for enhancing flow rates. Also, if installing on anything less than 200mm centres, inverted is the only layout that allows for tightly packing in the pipes. On my current project, an MBC TF passive raft, the pipes are going in at 100mm centres to maximise water volume in the system ( to aid the operation of the ASHP + cooling ) and that can only go in via inverted at that distance apart. If going DIY then serpentine may look simpler, but inverted really is a doddle to lay, me imho easier than serpentine as you’ve not got to perform so many ‘U’-turns ( which are difficult / easier to kink the pipe with when performing scores of them with each loop ? ).