sonicboom

Hi All, Has anyone got any pointers on this ? I was going through the docs for the 100-w B1KF, and there is plug 96 which can be configured to external demand, whereby a thermostat can be connected to it. There is also a cylinder thermostat but it has (system) in brackets so I don't know if that would even function in the combi variant). The plan is to have a NO value on the CH side and a NC on the cylinder. Leave CH Thermostat as is with weather comp etc and hook up the themostat to plug 96 and cyl stat to X5 in the boiler.

Are there any specific fan systems designed for this ?

There are 5 people in the house at the moment, but it'll drop to 4 in the next year or two. Interesting you say 30m3 since the PIV worked very well at close to that rate too (120m3/hr for 5 people). Although I would prefer to run it lower and reactively increase it based on humidity since not everyone is at home all the time. Good idea ?

What test is this an how is it performed ?

Sorry, missed @JohnMo airtightness question - long day. Its extremely air tight, to the point the PIV is not really working any more.

Sorry, 2 floors, each 2.4m.

My property has a floor area of 100m2, and volume of approx 480m3. I have a PIV and before the air tightening noticed about 35l/s is more than enough for the property. The question I would like to ask is, how do I select the proper size unit. I was thinking of going for a Brink Flair 450 but not sure if that'll be enough.

I was going through this list: https://database.passivehouse.com/en/components/list/ventilation_small Does anyone know what the reference temp is for the heat recovery percentage ?

I am running a low temp heating system (3kw heating + weather comp) with a viessmann 100-w boiler than can churn out 26kw in heating and 30kw dhw. Dhw doesn't go above 40c @ 4lpm which is about 7kw. It is frustrating that considering how low the energy usage is that the combi can only run dhw or heating and not both together. I am temped to remove the seal rings from the diverter value. Has anyone been ballsy enough to do something so drastic ? What possible issues could I come up against ? The alternative would be a cylinder but that has its own issues. It's annoying that viessman and co have introduced so much tech into newer boilers without thinking about the fact that lower consumption makes it possible to run both things at the same time.

Cool. What tool/gear do you use to monitor the temps ? and what do you mean by batch charging ? I am assuming you are using ashp, you must be getting some really good COP ratios with UFH. Are you doing UFH on 1st floor too (assuming you have one) ?

That image is excellent, thank you very much for that. The TItan's have an efficiency of about 88% - do you feel coolness as the temp drops to 0c ? This worries me as I like warmth and want as high an efficiency possible. What is your internal temp btw ? and are you running a low temp heating system ?

Thanks. So what is the floor area (m2) of your properties ? I was expecting the boost to need to be much higher than that - a little stumped. Some more questions if you guys don't mind: 1. Where is the bathroom extractor located (middle of the room, where the bath is) ? 2. Is it on the wall or ceiling ? 3. What is the diameter of the extractor ? 4. What type of grille are you using ? 5. What mvhr unit are you using ?

Its a 150mm inline fan and makes the bathroom chilly. You can feel the current of air being pulled from the feet to the torso, so I have no doubt it pulls a lot of air. Interesting, so I guess the humidity is so low in your property then ? Whats the flow rate for your setup and whats the boost flow ?

How do you guys manage hot steamy showers - can the mvhr keep up ? My current extractor pulls 560m3/hour to keep things at bay - any lower and the steam builds up quick. I don't like the idea of the entire house having to run at very high fan speeds because someone is taking a shower - especially if its at night or early morning.

Thanks guys. What about insulation of this form factor? the insualtion makes up the bulk of the size i.e. 50mm, so it still amounts to 125mm.

Does anyone know if this Is this a good unit ?

Can you recommend rectangular ducting - this might work. Does it need to be 225mm though ?

Its a single story extension with no way of access through the joists so would need to go out externally about 3-5m. I am not too keen on that - primarily aesthetics.

It's a 1960s build, and the property is extremely airtight in prep for mvhr. So there is no way around it then?

Thanks. It would work very well in a bedroom but the problem room is in fact the kitchen and I am not sure if it'll work as effectively since moisture is the bigger issue.

Has anyone fitted any dMVHRs ? are they any good ? I have a room that is too far out for MVHR so dMVHR is probably the most conducive solution, however, the efficiencies aren't very pleasing. I have seen PRANA claiming 96% efficiency but I don't know how that scales as the temps drop.

I use https://www.ebay.co.uk/itm/335374071609

Its probably useful to understand the purpose of the different types of insulation. Wool type insulations do not stop airflow, they slow it down. This allows for the trapped air to heat up but also for moisture to escape. Its primary use case is in attics because you want moisture that has seeped through to escape otherwise you risk mould growth. Foam type insulations stop airflow completely and convective heat loss is substantially reduced i.e. > 95%, and the primary focus is on conduction/radiation. Pipework should be using some type of foam insulation for this reason. Wool type insulation will help but you are losing heat through conduction, radiation and convection. You just won't get the numbers you want.

Thanks for the clarification. I will be extracting from 3 rooms, and supplying to 4. I've not gone as far as to think about pipe sizing, but current line of thinking is 90mm for extract, 75mm for supply.

The supply will be from a 150mm roof vent installed for the bathroom extractor. The exhaust will be in the bedroom right next to the unit.