Using MVHR for the first time

[jamieled]

We are hoping to get into the house very soon. I expect it will be some way off before I can properly commission the MVHR (set the flow rates etc).

 

Is there any problem with using the system unbalanced initially? Does it put more strain on the mvhr unit or can I just use it on a low fan speed and not worry about it?

cheers in advance.

[ProDave]

No problem at all. I ran mine for over a year before borrowing one of the forum's anemometers and setting it up properly.

 

I just did a "seat of the pants" intitial set up.  Leave the vents on the rooms with the longest pipe runs open quite wide, and the rooms with shorter runs, close the vents down a bit.

 

What I found when I set it up (if my memory is correct) was I was over ventilating the kitchen and under ventilating the bathrooms, but it did not seem to make much practical difference.

[ianfish]

Is there much variance in cost between systems?

 

We have identified 

 

2 wet rooms kitchen utility

1 isolated room mid house

1 toilet under stairs

 

2 bathrooms upstairs

 

What have others used?

Edited August 1, 2020 by ianfish
Copy n paste

[Bitpipe]

Mine was on for almost 2 years before balancing the vents etc.

 

8 hours ago, ianfish said:

Is there much variance in cost between systems?

 

We have identified 

 

2 wet rooms kitchen utility

1 isolated room mid house

1 toilet under stairs

 

2 bathrooms upstairs

 

What have others used?

 

Like many here we used a system from BPC Ventilation that was based around the Vent Axia Sentinel range. There are cheaper and much more expensive solutions.

 

The ducting etc should be the same cost whatever unit you choose, typically you will double duct the extracts and single duct the supply (one per room).

 

Are you planning to DIY install?

[Pete]

17 minutes ago, Bitpipe said:

Mine was on for almost 2 years before balancing the vents etc.

 

 

Like many here we used a system from BPC Ventilation that was based around the Vent Axia Sentinel range. There are cheaper and much more expensive solutions.

 

The ducting etc should be the same cost whatever unit you choose, typically you will double duct the extracts and single duct the supply (one per room).

 

Are you planning to DIY install?

I have not doubled up extract and single to supply. I have the same amount of extracts to supply throughout the house so I assume it is easy to balance? I have not bought my vent axia but will be soon. It is a BPC designed system.

[dpmiller]

Depends on the duct lengths. Fans tend to make positive pressure more easily than vacuum,  so restriction is seen more on the extract side.

[Bitpipe]

8 hours ago, Pete said:

I have not doubled up extract and single to supply. I have the same amount of extracts to supply throughout the house so I assume it is easy to balance? I have not bought my vent axia but will be soon. It is a BPC designed system.

 

I had 14 extract ports on the manifold (7 double runs to kitchen, bathrooms & utility) and then 13 supply ports (single runs) and it all balanced easy enough.

 

The extracts easily exceeded BR min requirements.

 

When you get round to balancing the system, the order you normally do things is thus:

 

1) confirm BR min extract rates to kitchens & bathrooms (restrict ceiling vents if required - i.e. excessive)

2) balance supply & extract (by tweaking supply ducts as you've set the extracts in step 1)

3) confirm whole house ventilation rate (by adjusting central fan speed).

 

 

[Nickfromwales]

8 hours ago, Pete said:

I have not doubled up extract

Has this passed B-Regs on such low volume airflow from the bathrooms? I only fit a single run for an extract if it's a cloakroom and less than a few metres to the plant / manifold. Every single bathroom has always had; double runs to a single valve, or two independent runs to two separate valves in the same room ( for a larger bathroom ) and same for kitchens ( dual or split dual ). Makes things a LOT quieter on boost too.

Edited August 2, 2020 by Nickfromwales

[Pete]

2 hours ago, Nickfromwales said:

Has this passed B-Regs on such low volume airflow from the bathrooms? I only fit a single run for an extract if it's a cloakroom and less than a few metres to the plant / manifold. Every single bathroom has always had; double runs to a single valve, or two independent runs to two separate valves in the same room ( for a larger bathroom ) and same for kitchens ( dual or split dual ). Makes things a LOT quieter on boost too.

I did not explain myself properly, yes I have double extract from bathrooms. I have mainly double supply ducts and double extract which was different from what @Bitpipewas saying he had done