MVHR running properly???

[joe90]

@Ed Davies thanks mate, didn’t realise an imbalance would cause such an effect, yes there is a “gadget” next to the MVHR with a screen and some data. I have turned the MVHR off and will give it 24hrs to see if temps stabilise. If I don’t report back we have secumbed!

 

note, another great example of the world of information this forum gets from such knowledgable members. Thanks.

[ProDave]

11 minutes ago, joe90 said:

, yes there is a “gadget” next to the MVHR with a screen and some data.

What is this gadget you speak of?

[Gone West]

15 hours ago, AliG said:

If you think about it, MVHR is always cooling down your house (assuming outside is colder than inside). The more it runs, the more cold air it brings in, it just isn't as cold as it might be due to the heat exchange capturing energy from the extracts.

 

We're lucky because our MVHR has a built in EASHP and the supply air temperature is never below room temperature. It also automatically turns off the supply fan if it is unable to deliver air at or above room temperature.

[joe90]

Well we survived the night!, the upstairs temp has risen by about 2’ which makes about 18 upstairs which is acceptable (to me). I have had a thought about balancing and (correct me if I am wrong) the air into and out of the building is controlled by the speed of the two fans, the balancing is making sure all rooms accept and remove similar amounts? I have read on this forum that people have set their MVHR to shift less air than the regs would stipulate. I must admit I was expecting to feel “groggy” this morning due to lack of fresh air (like we used to in our last house that had no trickle vents) but we did not!!! I must get on with balancing the system and controlling the amount of air shifted. On a different but similar vein, if the restrictors are closed a bit to restrict air will this put strain on the fans?, would it not be better to turn down the fans (if possible). Answers on a post card to..........

[PeterW]

You won’t strain a fan as the design means it can push against a closed port as they are low displacement fans. 

 

Can you adjust the fan speed on those units ..?? 

[joe90]

16 minutes ago, PeterW said:

You won’t strain a fan as the design means it can push against a closed port as they are low displacement fans. 

 

Can you adjust the fan speed on those units ..?? 

Yet to enter the loft and find the “gadget” for monitoring and read the spec on fans (I have my chores to do first ?).

[Gone West]

@joe90 This table shows what I used to set up our ventilation and may be of some help as a starting point.

 

MVHR Calculation.pdf

[Ed Davies]

Just sent Steamy an email drawing his attention to this thread. Hope he can chime in.

[joe90]

Thanks guys @PeterStarck and @Ed Davies.

[joe90]

Just an update, I have had the MVHR off for the last 48hrs and noticed no degradation in air quality (apart from being reminded about yesterday’s bacon sandwich!). The bedroom temps are stable at about 2’ above what they were when the MVHR was on!!! Balancing the MVHR and setting the correct rates or on my very long “to do list”.

[ProDave]

@joe90  You have the Lossnay unit same as me I believe?

 

You can speed up both the intake and exhaust fans by using the dip switched on the board.  I don't have the exact manual as the ones on line are for a very slightly different control board.  But with the unit on, go and turn each dip switch on one at a time, and you will find one speeds up the inlet fan a bit, and another speeds up the exhaust fan a bit.  Handy to balance it if there is a difference between inlet and outlet airflow.

 

I have not balanced mine yet either.

[Simplysimon]

i' glad this topic has been posted, i am (was) intending to only have ufh downstairs but this has got me thinking whether i should put in post heating in the bedrooms just in case. walls and roof to u value of 0.1 and a Zehnder Comfo Q350 R . i had already thought to put elec towel rads or ufh mats in the bathrooms to bring them up a bit, any thoughts?

 

i reckon water post heaters https://www.paulheatrecovery.co.uk/components/post-heater/decentral-water-based-post-heater/ too much faff but these  https://www.paulheatrecovery.co.uk/components/post-heater/de-central-electrical-post-heater/ would do. have and not need as opposed to need and not have, but will i need them as woud rather do without the extra cost?

[joe90]

I like the look of the individual room post heaters, frankly with my MVHR off the bedrooms are 2’ warmer and acceptable, so o need to balance my system properly, as cable is fairly cheap, wire for them In case you decide to instal them, if you don’t need them the pin all is good.

[Gone West]

13 hours ago, Simplysimon said:

i' glad this topic has been posted, i am (was) intending to only have ufh downstairs but this has got me thinking whether i should put in post heating in the bedrooms just in case. walls and roof to u value of 0.1 and a Zehnder Comfo Q350 R . i had already thought to put elec towel rads or ufh mats in the bathrooms to bring them up a bit, any thoughts?

 

Our walls and roof U value is 0.1 and our main heating is supplied by electric towel rails in the bathrooms and a small area of electric UFH in the kitchen. This is so that the rooms with a ventilation extract are always warm. We are lucky because our ventilation unit has an EASHP built into it so the supply air to the living rooms is never below room temperature. I would have thought that an electric post heater would be a good idea. When designing our house, before I had found the Genvex Combi, I had looked into using an electric post heater to ensure the ventilation supply air was always warm.