Embarking on a diy MVHR design install

[hoymp]

Hi all I am new here. Currently, I am extending and remodelling our terrace house.

 

I have had a look at the design for an MVHR system see below my calculations I have based it on information that I have put together from looking on this forum

 

Originally I had thought that I would use 75mm ducting. However, looking into it a bit more it might be better to use 90mm. if my calculations are correct then I would only need to double up the ducts to the Kitchen and Living room.

 

I have looked at the most onerous duct (Kitchen) and have evaluated that the Pa over 12m with three bends and vent would be approximately 50.

 

if anyone can see if I am going off track I would love to know.

 

 

Below is the ducting and outlet for the ground floor. Red for extract, blue for supply 

 

Bellow ducting and outlet for the first floor 

[ToughButterCup]

Welcome.

I see you have found the delight and strength there is to be found in reading BuildHub.

... my calculations [ ... ] based [...] on information [...] put together from looking on this forum...

 

They say that T'internet is the place for shared ignorance.

That doesn't last long here: and for good measure we usually add TakingThePiss to our online offering. Have you thought of asking a company to specify and quote ? I have a feeling you might have - but just in case...

 

Welcome anyway

Ian

[hoymp]

hi@ToughButterCupindeed I have spoken to a couple of companies and as suspected received differing approaches, and thought I could have a go at making a complete balls up of it on my own.

[Sparrowhawk]

Welcome, it looks good and you have nice slow flow rates on boost. Slower than I'll have on boost at "design speeds" (not to be confused with this forum's idea of actual running speeds).

 

You have a unit problem in column D of the spreadsheet, Volume needs ^3 not ^2. I'm not sure with J2 and J3 what those figures are?

 

Are you planning to mount the MVHR above the stairs or in the loft? Good luck with getting the ducts coming out of it as you've drawn, I am fast coming round to the idea of home-made distribution box (as someone on this forum has done) to get the pipes out in the directions I need!

 

Edit: Looking at your floor plans, which direction do the first floor joists run? Side to side?

Edited August 29 by Sparrowhawk

[ectoplasmosis]

Can we see more detail of your terrace refurb in general? Very interested.

[hoymp]

@Sparrowhawk Ah yes sloppy copying of cell format with the volume. J2 and 3 were me looking at the areas of the rooms with supply or extract. not that they do anything really in the table.

 

the MVHR unit will be placed in the loft and the duct runs are most definitely diagrammatic at the moment. As for the joist direction, there is a false ceiling, which enables the ducts to run free. other than an annoying steel beam the only place the direction is an issue is the living room.

 

I am currently looking at the duct routes to see if I simplify it

[hoymp]

@ectoplasmosis I will post up a bit more later, we are building a timber frame extension to the rear to allow for a ground-floor bedroom for the mother-in-law.

[Sparrowhawk]

@hoymp existing false ceilings, lucky you! Downstairs I am having to add 2, and flex ducting into one run between parallel joists across the more open plan section to prevent having to lower the lounge/dining room ceiling.

[hoymp]

@Sparrowhawk Indeed the false ceiling was a design decision to hide any ducting and steel.