Pre filter between MVHR vents and MVHR unit

[Russdl]

@PeterW something else that occurred to me looking at that inline filter box you linked to, that would introduce an obvious cold bridge inside my warm roof. I'd never really considered that with my ply/MDF version, but I guess I could have issues there if I go down the ply/MDF route?

[Russdl]

3 minutes ago, Nick Laslett said:

Walking around my Village today and all the wood burning

 

I'm only trying to filter out flies and fluff at this stage, but that could well become a separate issue for us.

[PeterW]

15 minutes ago, Russdl said:

@PeterW something else that occurred to me looking at that inline filter box you linked to, that would introduce an obvious cold bridge inside my warm roof. I'd never really considered that with my ply/MDF version, but I guess I could have issues there if I go down the ply/MDF route?

I had to insulate a metal box due to condensation - same as the ducting as it’s surprising how quick you end up with pipework with a lot of condensation on it. 

[Russdl]

@PeterW I'm using the Ubbink foam stuff, so that's already insulated, I wonder if my little wooden box pre-filter will cause me condensation issues????

[SteamyTea]

9 hours ago, Russdl said:

I wonder if my little wooden box pre-filter will cause me condensation issues????

It is not the material, it is the temperature and humid hitting the dew point.

 

Dew Point Temperature = Observed Temperature -((100 - Relative Humidity) / 5)

 

OR

 

Dew Point Temperature = ((HUMIDITY/100)^(1/8))*(112+(0.9*TEMP))+0.1*TEMP-112

Edited November 16, 2020 by SteamyTea

[Russdl]

Ummmm, thanks for the equations  @SteamyTea can’t quiet see how they can help me? 

(the answer is, your not going to like this...            42)

 

In more practical and less mathematical terms, how can I use those equations to inform my decision on whether to build my wooden box pre-filter or not? Shoving a finger in the air I reckon I’ll be fine. 

[Onoff]

MDF won't like condensation. Might has well make it from cardboard. There's plans for a homebrew MVHR floating around that uses ply and sort of tilts the construction that I guess helps with any condensation. You might be able to pinch some construction tips.

 

https://www.builditsolar.com/Experimental/DIYHRV/DIYHRV.htm

 

 

[joe90]

I used ply fir my distribution/silencer box, if your worried about condensation then paint it (lots). 

[SteamyTea]

28 minutes ago, Russdl said:

In more practical and less mathematical terms, how can I use those equations to inform my decision on whether to build my wooden box pre-filter or not

You can't.

It comes down to the statistical probabilities of the stochastic nature of weather and house usage.

 

Or just make of from plastic.  Easy to get a sheet of PVC and some 'plumbers plastic pipe glue'.

 

[joe90]

Or use clear acrylic sheet then you can see if there is any condensation ?

[SteamyTea]

21 minutes ago, joe90 said:

clear acrylic sheet

Needs a different glue.

 

Ow about a cheap plastic box, the kind they sell in PoundStretchers (which is misnamed as a £ is a fixed size and mass, though, due to FOREX, can have a different purchase price, even if the purchase price parity is similar)

[Russdl]

Thanks all. 
 

I wasn’t at all concerned about condensation until @PeterW posted the link to the galvanised filter housing, then I thought about it, I’m sure the galvanised option would be a problem without plenty of insulation. 
 

My proposed timber filter box ( @Onoff which will now definitely be ply, not MDF) will be painted. Or @joe90 clear acrylic, good thought. I’d be able to see any condensation and crud build up! @SteamyTea I’ve got plenty of airtight tape that would join acrylic, maybe a timber/acrylic combo is the way to go...

 

Oh, and @SteamyTea 

 

1 hour ago, SteamyTea said:

stochastic

is that a real word?

[SteamyTea]

1 minute ago, Russdl said:

1 hour ago, SteamyTea said:

stochastic

is that a real word?

Oh yes.

https://en.wikipedia.org/wiki/Stochastic

[joe90]

Looking forward to seeing how you progress with this little project, keep us informed (and loads of pics) ?

[Russdl]

1 hour ago, joe90 said:

Looking forward to seeing how you progress with this little project, keep us informed (and loads of pics) ?

Only if it turns out ok, otherwise I shall let this thread wither on the vine and pretend it never happened. 

Edited November 16, 2020 by Russdl
Stoopid spellcheckautocorrectthingy

[Russdl]

41 minutes ago, SteamyTea said:

 

48 minutes ago, Russdl said:

1 hour ago, SteamyTea said:

stochastic

is that a real word?

Oh yes.

 

 Thanks, every day is a school day. 
 

I’m struggling to see how I’m going to fit it into my daily conversation, but I’ll have a go ???

[SteamyTea]

6 minutes ago, Russdl said:

 Thanks, every day is a school day. 
 

I’m struggling to see how I’m going to fit it into my daily conversation, but I’ll have a go ???

Just talk about cloud.

or lottery ticket winners.

 

[Onoff]

12 minutes ago, Russdl said:

 Thanks, every day is a school day. 
 

I’m struggling to see how I’m going to fit it into my daily conversation, but I’ll have a go ???

 

I know, it's a bit random isn't it!

[SteamyTea]

Just now, Onoff said:

 

I know, it's a bit random isn't it!

Or chaotic

[Russdl]

The over engineered MVHR pre filter arises from the gash bits of MDF offcuts that litter the house. Some finishing off to be done and it’s kept my son off the streets making stuff for his deluded dad. 
 

 

[Russell griffiths]

Please tell me you will tape and paint that wall before you fit it. 

 

 

[Nickfromwales]

11 minutes ago, Russell griffiths said:

Please tell me you will tape and paint that wall before you fit it. 

 

 

I’d be more worried about painting the inside of that splenderific item with a few coats of oil based paint.

[Bonner]

That’s a fine piece of woodwork and if it doesn’t do as a filter, you can always use it as a commode ?

[Russdl]

@Russell griffiths I will (well, somebody will)

@Nickfromwales I will. 

@Bonner I may. 

[Nickfromwales]

2 hours ago, Bonner said:

you can always use it as a commode ?

Might block the filter material up a bit too quickly?!?