MVHR & New Installation

Old Time spark

New Member
Hi all,

I am a new member so forgive any mistakes, but wonder if anyone can help advise me, I am a retired electrician doing a full renovation with a rewire of a property. I engaged an approved electrical contractor to carry out all wiring and installation of a whole house MHVR system.

Re the MVHR; (Vent Axia Kinetic) with three bathrooms in my home, the contractor only put one small semi flexible duct to each of the two wings (each extension has a bathroom and bedroom in it) I questioned how you can put warm dirty air from the bathroom, and then warm clean air into the bedroom down the same duct.

The answer was,
As for the ventilation the fan that gets fitted in the bathroom have an external baffel and filter so that it cleans the wet air in itself and pushes the clean
air back through into the ducting system. Which is done at 2nd fix stage. I picked this system due to the complexity of running 2 additional pipes to
each wing, which cost wise on labour and ducting would be more expensive as well.

Am I wrong thinking this will not work right, how can cold air go down the same pipe as warm air is coming out of?

Paying several thousand pounds for this system alone I worry this will not give the efficiency promised. Suddenly I was informed after the roofer finished I needed to install vents in the slate roof, the electrician supplied these plastic vents but now says it an extra.

Onto wiring, so many parts I worry about, in my day you would never run low voltage cables (telephone, alarm, AV, etc) with ring main cables, supply cables, especially in the same holes, the answer is they are double insulated, and will not be an issue.
No cables are protected, and one even runs inside an old copper water pipe, where the ends have been hammered back, walls have been plaster boarded with no cables for lights, sockets cut out or marked.What point should first fix take you to now?
Internal walls have cables run down to feed outside lights, which I am told will have plasterboard glued over with no chasing, fixing or even the cables flat.
Outside lights planned to be below the PIR detectors, surly the heat from the down, up-lighters will trigger the PIR?

I am at a loss, while I know I am out of date now, I have no idea who to ask or turn to, wrote to NICEIC but no reply, have the regs changed that much, any suggestions would be appreciated or to be pointed in the right direction.
I do not want to upset the electrician, sadly I cannot add photos here to explain better then I can.

Cheers
 
Onto wiring, so many parts I worry about, in my day you would never run low voltage cables (telephone, alarm, AV, etc) with ring main cables, supply cables, especially in the same holes, the answer is they are double insulated, and will not be an issue.

if the cables are run together ELV and LV need to be separated either by another layer of insulation, ie run the ELV cables in conduit or trunking etc, or separated by 50mm. Alternatively the LV cables need to be SWA or the such, not really practical in a domestic.

The double insulated thing comes up a lot and is often misunderstood. It should be insulated to the highest voltage present.

Tbh if the spark is doing this kind of thing it makes me wonder where else corners are being cut.

Not sure on the rest tho.
 
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if the cables are run together ELV and LV need to be separated either by another layer of insulation, ie run the ELV cables in conduit or trunking etc, or separated by 50mm. Alternatively the LV cables need to be SWA or the such, not really practical in a domestic.

The double insulated thing comes up a lot and is often misunderstood. It should be insulated to the highest voltage present.

Tbh if the spark is doing this kind of thing it makes me wonder where else corners are being cut.

Not sure on the rest tho.

Hi,
Many thanks much appreciated, the 12v alarm cables and telephone cables etc were installed in 20 - 25mm holes the spark has shoved his 2.5 / 1.5 mains through the same holes (I assume to save him drilling his own holes) when I protested he said they are fine, as I dont know the new regulations I had no grounds to disagree. To be honest seeing what is being done would have never happened in my day. Added a photo where an old copper water pipe was used through a wall.
Great to know I am not going mad!! have a great day, and thanks
 

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With the vent system, the warm stale wet air is usually taken from the room that gives the most pollution to the air, in this case the bathroom. The flow of fresh warm air from the system will be directed into the main living area and preferably at a point as distant as possible from the extract point. Leakage and filtration allows the air to move towards the extract in the bathroom, picking up moisture and pollutants as it goes.
 
Cheers, Looks like it, he is approved and was recommended, not sure who would take over his job now!
If he is registered with one of the part p schemes then his work will be guaranteed and insured so if he really has made mistakes then you can get the situation resolved. Find out who he is registered with and then let them know your concerns. Strangers on the internet calling for him to be thrown off the job is just hysteria and that won't help you get your house wired
 
Old Time spark, The idea of MVHR is you should have Inlet vents into some rooms along with Outlet vents in wet/hot /warm rooms.
As Bob said the warm stale air is sucked out of warm/damp rooms, bathroom/kitchen, then goes through the Heat Exchanger.
Then the warmed air is blown back into other rooms, as this is Fresh warmed air from the Outside.
So the system basically sucks & blows. But with fresh air.

You should have then, an Inlet air pipe, from the outside, to the Heat Exchanger, & an Outlet pipe exiting the house via wall or roof, which would be the Stale air.
 
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