Some of you may have noticed that I have been talking about making a MVHR unit. Well this is the data my first attempt.
It currently has no control over the incoming air (cold), the outgoing air (hot) is on a timer on the bathroom fan. You can see exactly when the bathroom is used on this chart and work out how much tea I drink if you are so minded.
Between 10:10 and 11:15 I kept the fan on constantly. The two spike before hand were shower times, guess who has the smaller spike?

The unit is pretty basic, just some plates in a box, a couple of fans and some pipe. Lots of room for improvement, tomorrow I shall go and get another fan with a timer on it.
Comments and suggestions welcome.

Efficiency has been calculated this way:
μt = (t2 - t1) / (t3 - t1)
where
μt = temperature transfer efficiency
t1 = temperature outside air before the heat exchanger (ºC)
t2 = temperature outside air after the heat exchanger (ºC)
t3 = temperature inside air before the heat exchanger (ºC)
 
 

I think, because there are no baffles/flaps, and there is a ±0.5 on the iButtons also sods law being what it is, plus up to a minute out on the temperature reading that the accuracy is not that great (5 minute sampling). After tomorrow when I get a new fan should yield some better results.

Just used http://www.engineeringtoolbox.com/heat-recovery-efficiency-d_201.html for the efficiency calculations.
Think that should be the classic 'up to' on the efficiency, you do get the greater efficiency with the lowest energy recovery by the looks of it.

This is the real outside temperature.
 
 

I better get working on the CAD then. Thanks

Painted steel plates, expanded polyurethane sheet (celotex like), silicone sealant, some 150 plastic pipe, some flexible pipe, couple of bathroom fans and a cut finger.
MkII will be a lot better.
I have drawn it up in Turbocad 17 but shall post it up here as a sketchup file (if I can zip it enough).
But here is a picture to be going on with.
 
 
 

Posted By: joe90I love it, I am a real build it yourself fan and love what you are doing, I may not understand all the "numbers" but I will leave that to you and others as long as you post you're design for the unit and how you built it." alt="" src="http:///forum114/extensions/Vanillacons/smilies/standard/bigsmile.gif" >

Totally what he said.

I never understand all the maths, but show me a diagram and I'm away. Thank heavens there are people as awesome as the OP to work these things out. Thank you :D

Posted By: Cav8andrewyou weren't set designer on early Doctor Who series by any chance

Funny you should mention that, I have done some film work in the past and made a Dalek once. Did the helmets for Krull and some reindeer parts for Santa Klaus the Movie. That brings back memories.
Give me an 8 by 4 sheet and I can make anything

Alien V ST MVHR I see a franchise !

Posted By: Cav8andrewAlien V ST MVHR I see a franchise !

I see another cut finger

and me

Me too. Any chance you put a copy in the scetchup 3D warehouse.

Or this:

http://www.greenbuildingforum.co.uk/newforum/?PostBackAction=Download&AttachmentID=2741

but not this:

http://www.greenbuildingforum.co.uk/forum114/?PostBackAction=Download&AttachmentID=2741

ST: “is it a similar problem that we had with Jeremy's zipped files?”

Yes. “forum114” version has the same line-feed character stuck on the beginning which upset the archive manager for me. Downloading the “newforum” version opened in the archive manager then double clicking on the .skp file opened it in SketchUp just fine.

I'd strongly recommend the use of layers in SketchUp to allow showing cutaway drawings easily.

Opens fine for me in sketchup.

Andrew it has opened in my sketchup. Have you got sketchup?

Full 3D that I can manipulate

Hi, if anybody is interested here are some links to in France for a DIY MVHR - in France these are called "VMC - double flux" ( 2 way mechanical ventilators).

http://vmc-double-flux-auto-construction.blogspot.com/

there's another at http://www.autoconstruction.info/techniques/energie-chauffage-isolation/la-fabrication-d-un-recuperateur , which is built using honeycombe plastic pannels, rather than aluminimum.

There's plenty of pictures, and if your French is not up to it, just use Chrome browser and click to translate it.

regs

Richard