Additional single room MVHR for 'far away' room

[tanneja]

Hi all,

 

Am very close to ordering a whole house MVHR from BPC.  As a reminder our project is a renovation, so the retrofit is a challenge.  Speaking with my builder, the concessions we would have to make with boxed sections through the main living space, to get MVHR to the further part of the house, is undesirable.  I am still seeing what can be done if we use oval pipes, but still it may be very tricky.

 

What are the likely issues I would encounter through having a single room MVHR in that problem far away location, given it would be linked to the rest of the building which is serviced by the whole house MVHR?  Will there be additional balancing problems?  Or is my only issue the cost of the additional single room unit and having 2 sets of unit filters to manage?

 

Many thanks

 

[tanneja]

I will be calling BCP later today to see what my options are, if people are considering decentralised units it feels like the only downside of a deparate single room MVHR for part of our property will be the extra cost and burden of two sets of filters. 

 

Just so I am clear, are the combinations of ducting available are 75mm circular, then 51mm x 114 oval, then have I seen on a post mention of 215 x ??

 

Many thanks

James

[Nickfromwales]

10 hours ago, tanneja said:

I will be calling BCP later today to see what my options are, if people are considering decentralised units it feels like the only downside of a deparate single room MVHR for part of our property will be the extra cost and burden of two sets of filters. 

 

Just so I am clear, are the combinations of ducting available are 75mm circular, then 51mm x 114 oval, then have I seen on a post mention of 215 x ??

 

Many thanks

James

I've used 225x25mm a few times in passive builds where there has only been the 35mm service batten depth to play with. 300x25mm is also available if the runs are excessively long, but I know the dynamics for airflow aren't favourable with rectangular vs round so you'd need to do some checks for airflow vs distance inc deductions for bends etc. These guys do the fittings so assume the duct too?

I am super-sceptical about retro-fitting MVHR into refurbishments though, at least anything worse than EnerFit standard refurbs, and would warn against it if you cannot get the 'air-tightness' addressed properly ( consistently ) according to the systems minimum requirements. 

 

 

[tanneja]

Thank you @Nickfromwales, I won't know for sure what air tightness we have until the build is done, but given we are pouring new solid floors, adding EWI, new triple glazed windows (no trickle vents) and new rood and ceilings throughout, it is almost a new house.  I have my fingers crossed that trying to bring these features together results in a house that 'works' as it should.

[Nickfromwales]

1 hour ago, tanneja said:

Thank you @Nickfromwales, I won't know for sure what air tightness we have until the build is done, but given we are pouring new solid floors, adding EWI, new triple glazed windows (no trickle vents) and new rood and ceilings throughout, it is almost a new house.  I have my fingers crossed that trying to bring these features together results in a house that 'works' as it should.

MVHR?

[tanneja]

1 hour ago, Nickfromwales said:

MVHR?

Sorry, I don't follow, yes MVHR planned to combine with those other home revisions, have I misunderstood you?

[Nickfromwales]

3 hours ago, tanneja said:

Sorry, I don't follow, yes MVHR planned to combine with those other home revisions, have I misunderstood you?

Nope. Sorry, was typing whilst being nuked by the sun whilst fitting PV ?. The questions been answered.....you’re having MVHR ?. Just wondered as you mentioned not having trickle vents. 
Off to find some after-sun lotion. I’m nicely toasted ?.