Setting up / balancing my MVHR

[HerbJ]

That's correct. Sizing MVHR is not an exact science and it seems prudent and sensible  to look at various methods/standards to achieve a reasonable and practical design approach - that is what the more experienced suppliers/designers do.

4 hours ago, ProDave said:

Yes sorry @HerbJ , because your design was done by PaulScotland I put 2 and 2 together and made 5 and assumed it was to Scottish regs.

Ah, I can see understand your thought process -  I believe the md of Paul Scotland is German and he is very experienced, bringing a  sensible and pragmatic approach to MVHR design, so looking at the design from both UK BR requirements and DIN standards. It's not something you may get get from many of the UK suppliers!

[Bitpipe]

Very simply, I went through this process:

 

1) measure existing per room and total supply / extract

2) check that min room extracts per regs met (I way exceeded them all)

3) tweak rooms to balance supply / extract

4) adjust fan to get min ventilation reqs - note measurements and revert fan speed to comfort settings.

 

Probably took 3 iterations of measuring each room.

[ProDave]

9 hours ago, Bitpipe said:

Very simply, I went through this process:

 

1) measure existing per room and total supply / extract

2) check that min room extracts per regs met (I way exceeded them all)

3) tweak rooms to balance supply / extract

4) adjust fan to get min ventilation reqs - note measurements and revert fan speed to comfort settings.

 

Probably took 3 iterations of measuring each room.

Yes but this has stalled for now as nobody can tell me the SCOTTISH building regs minimum room extract rates for mvhr. It even stumped the duty building control officer that I spoke to on the phone yesterday, he has gone to find out.

 

I will for now set it up to comply with English building regs and hope that is not too far out when the information on Scottish regs is eventually found.

[PeterW]

6 minutes ago, ProDave said:

Yes but this has stalled for now as nobody can tell me the SCOTTISH building regs minimum room extract rates for mvhr

It’s all here ..??

 

https://www.gov.scot/publications/building-standards-2017-domestic/3-environment/314-ventilation/

As per usual, it refers to an outdated CIBSE standard (2001 vs 2016) but if you want to read the full CIBSE standard there is a copy here 

 

 

[ProDave]

Yes I have read all the linked documents.  The link to a BRE one that says the trickle rate should be 0.5 ACH.  That is about the only useful bit I have found.  They refer to section 3 of that CIBSE standard. It does not have a section 3.  And what is in sections 1 and 2 is way over my head.  There might be something buried in there that tells me the ventilation rates required, but I could not find it.

[Bitpipe]

1 hour ago, ProDave said:

Yes but this has stalled for now as nobody can tell me the SCOTTISH building regs minimum room extract rates for mvhr. It even stumped the duty building control officer that I spoke to on the phone yesterday, he has gone to find out.

 

I will for now set it up to comply with English building regs and hope that is not too far out when the information on Scottish regs is eventually found.

 

Just hold your nose and go English

[ProDave]

4 hours ago, Bitpipe said:

 

Just hold your nose and go English

It's not a case of holding my nose. I AM English.  At the end of the day I want to set it up to demonstrate compliance with building regs. Only nobody yet seems to know what that is in Scotland.  No wonder nobody seems to be asked for any paperwork.

[ProDave]

Okay I have done some adjusting. The latest version of the spreadsheet is attached.

 

I am now using the next fan speed up for trickle ventilation, and that, with recalculating the floor area (removing the room above the garage that is outside the mvhr envelope) the trickle rates now comply (with English regs at least)  I will however be reverting to the slower fan speed for trickle ventilation and will check later how that complies with PH ventilation rates.

 

I am now using the fastest fan speed for boost (which we actually use for bathroom boost) and the extract rates again pass English regs.

 

I have done some adjusting to speed up the kitchen rates and slow down the bathroom rates.  I would like to slow the utility rate a bit but that vent is now as closed as it will go.  I have also slowed bedroom 3 which is much smaller and not used as a bedroom.

 

I think that will do for now until I get some figures for Scotland.

Willow_burn_Ventilation.xls

[Jeremy Harris]

FWIW, the instructions for our unit indicated that fan speed 1 was only for use when the house was unoccupied, speed 2 was the normal background ventilation rate, speed 3 is the normal boost speed (humidity controlled in our case) and speed 4 is 100%, used infrequently for purge ventilation.

 

I adjusted speed 1 right down to about 10%, enough to keep things fresh with no one at home, handy for use when we go away.  I initially set speed 2 to meet building regs, then backed it off later, so that it runs at around 0.4 ACH (seems about right for us). Speed 2 is something like 30% speed, I think.  Speed 3 is set to 75%, which seems fine for normal boost. I think we've only used speed 4 once, when we didn't manage to turn the MVHR off when someone nearby had a bonfire, when the extra ventilation after the bonfire smoke had died down helped to clear the air in the house quickly.

[ProDave]

We use speed 1 as the normal rate which seems fine and the air is always fresh.  Speed 2 is now the "compliance speed"  speed 3 we use as the kitchen boost when cooking, and speed 4 is the bathroom boost when showering,

[ProDave]

Well Monday's phone call from Building control never happened.  I take it they either don't know the figures or don't determine it important enough to tell me.

 

So on that basis I have just amended the spreadsheet to remove references to "Part F" but otherwise leaving the compliance values the same.

 

If I am asked at completion for any documentation with regards the MVHR it will be met by "show me the figures stated in the 2013 Scottish building regs that I have to comply to"

 

[Savage87]

I wouldn't worry to much about it unless they ask you about it, my local BC said just go ahead and fit the unit..