Ventaxia Sentinal Kinetic BH airflow balancing

[JigsOrla]

Hello everyone! Was hoping to get some guidance on airflow volumes, as I'm just getting round to balancing all the vents. I've been refurbing our 85m2 house for the last year or so, it's a 3 bedroom old Victorian house, not too drafty in the first place, but as I've been replacing walls, floors, plumbing, etc, I've blocked vents and sealed gaps along the way as best I can, with the eventual MVHR install in mind. The kitchen and bedroom above it are part of a newish extension which are well sealed and I've got a couple of old fireplaces to seal up still. Condensation since we moved in had been a huge problem so this, and air quality, was my main concern. Even without balancing, all looks really good since turning on the unit a month ago.

 

 So with 4 supply vents and only 2 extract vents, I'm confused as to how to equalize the flows. Here's a chart I've adapted from another post:

 

 

1) I'm not exactly sure what my whole house ventilation rate should be for the normal supply speed. As you can see from my rough notes at the bottom, I've noted suggestions from 3 different sources and this is conflicting. Should I just aim for the middle? The building regs guidance seem way too high. Currently, the system is near silent and condensation has disappeared from bedroom windows and the front room wall. Maybe placebo but the old house smell in the entrance hall has also disappeared.

 

2) From the unit's defaults, I've increased extract to 35% and supply decreased to 25% . I've read you don't really want to imbalance the supply and extract fans too much - but it looks like with only 2 extracts I'd need to increase the speed even more until they equalize. Is this correct? Or best to have the fan speeds closer and just restrict the flows from the supply vents themselves?

 

Here's my adapted anemometer which works really well with the right seals (yes, that's the kitchen funnel) The conversions from m/s are specific to the meter using https://www.engineering.com/resources/air-flow-calculator/. 32.5mm radius if anyone's using that model.

 

 

Appreciate some guidance.

[JohnMo]

Your main bedroom I would do 40m³/h other bedrooms 20m³/h. That gives 80m³/h. I will get to lounge in a latter

 

Extract, kitchen 48m³/h and bathroom 32m³/h. So fully balanced and not over ventillated.

 

Lounge depends on your layout. Ideally you would've as through flow. That is excess air from upstairs (48m³/h) would flow through the lounge to the kitchen. For this to work you need a path from the stairway through lounge to kitchen. If that doesn't work because of layout, you need a supply in lounge and extra extract in bathroom and kitchen to balance flows.

 

Boost set 20% above normal 

 

Have you undercut doors?

[JigsOrla]

Hi John. The layout doesn't work as the doors from living room to kitchen are very close, so it wouldn't get much through flow. The lounge (living room) already has a supply vent so I'll either increase extract flows for kitchen and bathroom or consider adding an extra extract vent perhaps in first floor hallway to help with balancing and minimise fan speed differences. 

 

Yes, all doors undercut to 10mm.