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DIY MVHR - design, spec?


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Hi all,

 

Slight emergency for us in the sense our builder has just dropped a clanger that the MVHR he originally costed for £5700 supply & fit is now coming back to us at double this!!  

 

With plasterboarding on the horizon, I have very limited time to try and find alternatives, even though I have a couple of historical quotes from local suppliers for nearly 50% saving, though I am quite sure their timing would push the plasterboarding & project back a good few weeks - a very hard conversation I am losing with my wife.

 

As a result i'm stuck between a £4k bill to meet the timings, or save £4k and incur rent & hassle for probably a good few weeks  -  as a result I am looking at DIY.

 

I am pretty good with DIY and am very hands on, running the pipework seems fair enough. In terms of how I design the system I am concerned though. Some quotes have shown ''Y junctions' within the fabric of the ceiling, when I just thought all pipes would naturally run back to the central unit & a manifold there?

 

Looking at Vent Axia Sentinel & a second compact one for the two halves of the house, as per floor plan attached. Low height central entrance prevents one unit being used.

 

Just welcome how others approached this & how DIY start was researched on design, supply, and any 'gotchas' found when DIYing a MVHR system? Ironically enough, money is no real object when I look at a £4-5k discrepancy between Builder's CEF quote & my historical quotes from a couple of months ago....

3180_s4_100J_Floor Plan.pdf

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For simple DIY you want a radial system where semi flexible ducts run individually from each room vent back to a pair of plenum boxes near the actual MVHR unit.

 

Start by looking at https://www.bpcventilation.com/  That is where I and a lot of other forum members have bought from.  In my case the actual MVHR unit was an ebay bargain and I bought all the pipework, vent terminals and plenum boxes from BPC.

 

What aspect of your quoted install has doubled?  the parts cost, the labour, or both?

 

EDIT:

 

Just seen your quote.  Don't buy kit like this from an electrical wholesaler, get a new quote for supply only, radial duct system from BPC

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17 minutes ago, Andehh said:

but when I look at the CEF quote thats killing us


To use the phrase @Nickfromwales and I use regularly … at least Dick Turpin wore a mask…

 

The Sx unit on your quote is available on the internet with a 10 second search for £2200 inc the VAT… now work down your list and do the same - even using all the stuff they list (75% of which I am not even sure about) you can save 25-40% online. Same boxes, just not from CEF and your sparky (or whomever) quoting you list plus pricing …

 

Either BPC or Blauberg can do all of that for less than £3k - it’s not rocket science and whomever is selling you the need for £500 CO2 sensor modules needs to be be shown the door and a size 9… 

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Thank you so much guys!!

 

Just builder dropped the ball I think, he originally estimated £3k to supply (nearly 18 months ago admittedly) and CEF have come in at £9100.   I'm meeting him next week to discuss, but it generally works as he does all the bricks, mortar & construction stuff then he gets a couple of quotes from 'big' firms to do supply & install on the specialist stuff...ASHP, UFH, Roof, MVHR, etc etc and goes with the cheapest.... I dont disagree with this approach as specialist doing specialist work, but in this instance the MVHR quotes are too much for me to just accept.

 

Turns out I ran a quote from BPC which came back at £4500 odd a few months ago which I am pleased with (completely forgot). That was for one large unit, when I will need two smaller units, but it has at least given me some that I can salvage something here.

 

Do BPC do the full design & supply....and you simply follow the instructions & adapt it on the day for the specific properties needs?

 

Im hoping as it's ''just'' a tall bungalow, warm roof (though block internal walls) and webbed joists the installation shouldnt be that complicated!

Edited by Andehh
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2 hours ago, Andehh said:

gets a couple of quotes from 'big' firms to do supply & install on the specialist stuff...ASHP, UFH, Roof, MVHR, etc etc and goes with the cheapest....


That is a very dangerous route to go - there is zero incentive to hit your price point by the builder !! I can get a quote from 3 merchants and them be £3k / £4k / £5k but you’d accept £3k… but by looking properly the true price is £2k… you think you’ve got a good deal but you have overpaid !

 

My gut feel is your builder has got lazy and you’re just paying whatever he wants to charge - that isn’t good and you will get shafted.

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Just go on to eBay and type MVHR, there's loads on there for good prices. 

 

I have a similar system and layout to you with two systems.  Keep it simple, manual boost switches, you don't need £500 of CO2 sensor.  Just a boost switch outside each wetroom and in kitchen.

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1 hour ago, PeterW said:


That is a very dangerous route to go - there is zero incentive to hit your price point by the builder !! I can get a quote from 3 merchants and them be £3k / £4k / £5k but you’d accept £3k… but by looking properly the true price is £2k… you think you’ve got a good deal but you have overpaid !

 

My gut feel is your builder has got lazy and you’re just paying whatever he wants to charge - that isn’t good and you will get shafted.

 

Yeah, up until now everything has been on a fixed price more or less, this MVHR has been the first real scare tbh. The price up front was keen & the quality of him/his team has been very good so happy over all.

 

For this MVHR though -I do agree!

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2 hours ago, JohnMo said:

Keep it simple, manual boost switches, you don't need £500 of CO2 sensor.  Just a boost switch outside each wetroom and in kitchen.

 

Keep it simpler. 

 

No boost switches or other sensors on ours. 

 

The unit is in the utility room however and v easy to access to chance settings if needed.

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We found a local guy, who was about half of the quote builder came through with. Fortunately in very quick succession we confirmed the quote, found slots in his diary and IN THEORY it's only a 1 week delay by the time he installs come 3rd December. Just good fortunate I got quotes a couple of months ago as a precautionary plan B!!! 

 

Still a chunk of £2500 materials more then we intended, but a lot less then builder quotes via CEF.

 

Im on my 2nd g&t this evening... Damage recovery mode continues...:D

 

 

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  • 6 months later...
On 07/11/2022 at 19:26, Andehh said:

We found a local guy, who was about half of the quote builder came through with. Fortunately in very quick succession we confirmed the quote, found slots in his diary and IN THEORY it's only a 1 week delay by the time he installs come 3rd December. Just good fortunate I got quotes a couple of months ago as a precautionary plan B!!! 

 

Still a chunk of £2500 materials more then we intended, but a lot less then builder quotes via CEF.

 

Im on my 2nd g&t this evening... Damage recovery mode continues...:D

 

 

Any update? 

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Not much of an update. Both systems are installed and are due to be commissioned in a couple of weeks. Installer is a nice guy and was reasonably priced & quick to fit us in, but he has left a little bit more work for me to organise then I would normally be OK with...just with so much going on its hard to muster the energy to push back at times!

 

Hoping commissioning goes ok in a couple of weeks and away we go! :)

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