As a prelude to getting whole house MVHR, I decided to sort out the leaks in our 1963 house. I have thought of it as "pretty good", so almost didn't bother. But then the DIY leak test idea came along, and it seemed pretty easy to do - so why not ?
Anyway, here's a description:

First I needed a 12V 10A or so car radiator fan. Ebay is our friend for this one. Any big car fan, I got one from a Toyota something or other. I picked one that didn't come with a radiator attached, and the piccy looked like it could be attached to a flat plate ok, and that was cheap.
Then I picked a window to use - I've previously replaced all of the glass in our house, so I know how to take the windows out easily. I picked one in the downstairs loo - out of the way, so I could leave my "experiment" there for a while, and the family would just humour me.
Take out the window glass (usually easy if uPVC surround & you know how), and create a plywood blank the same size of the window. Pad it out with wood so it's the same thickness as the glass- we need a tight fit here, then fit the fan to the wooden window blank. Fit it to blow out, so that the house is depressurised, and leaks are easy to feel for.
I made a manometer too, out of a 2m length of 5mm diameter clear plastic tube. There's a U bend of tube in the house filled with water+a bit of quink ink. One end of the tube is in the house, the other is outside, both a metre or so away from the fan. 5mm height difference is equivalent to 50Pascals pressure difference between the two ends of the tube, and that's our target pressure.
I borrowed a variable power supply from work to drive the fan- but in practice a 12V car battery, or a 10A+ battery charger would do, just wouldn't be adjustable.
Anyway, here's a piccy of the installed fan. There's no finger-guard at the moment, so it's a bit of a health & safety nightmare.
Hope somebody out there finds it usefull !

and again, from outside. Blue plastic to keep out draughts when not in use.

Rob
That is brilliant. We should all agree on a standard Toyota fan and compare (Compair: make of compressors) results. Shall ponder how to calculate pressure difference to leakage to send me to sleep.

Does the fan have a part number on it? should be able to look it up on the interweb.

Just thought, an amp meter would show the air resistance, but may not be accurate enough. Shall ponder more.

I would have undone the six hinge screws rather than take the glass out!

The method will help find leaks but I cant see it giving results though it may be possible by comparative methods where progressively larger openings are formed of known size and working out on a graph the effects and subtending backwards to a base line?

Real air leakage tests use various sized openings in front of the fan as well as controlling the speed for a certain pressure. There is a complex relationship between the speed of the fan, the aperture and the air leakage that the commercial testing equipment calculates. See, for example, this report: http://www.doncaster.gov.uk/Images/sample%20report_tcm2-67593.pdf which was produced using Canadian equipment - see http://retrotec.com/large/Products/Software/FantesticPro.aspx

However, the DIY system is good for finding where the air leakage is taking place.

Paul in Montreal.

Anyone else think that all the sealing (fireplace, extractor fans etc.) before the test is a bit bonkers?

The fan actually was listed on ebay as:
Nissan 300zx z32 fairlady radiator fan
It's got a sticker with "Calsonic 9 Made in Japan" on it, can't see anything else identifying on it.
It's in decent condition, but it was only 99p, so will it's performance be like another one ?

Running it hard, with the window next to it first closed then open, I get:
15V@11.8A, pressure drop 65Pascals, airflow ?
15V@10.8A, pressure drop 20Pascals, airflow massive

I don't think the current is a good indicator of airflow or pressure drop. It would be very handy to have pressure v flow for a given supply voltage for the fan, maybe I'll get around to that somehow - I'm not sure how at the moment, as I don't know how to accurately measure the airflow. I could perhaps get it vaguely right by putting a cowl on the outside so I could hold a massive plastic bag to it, and time filling it.

For now I think I'm happy using it find leaks. So far:
Front & back door need new draughtproofing
keyhole covers
All sockets leak - bodging this with lots of silicon sealant
Floor above inset front door leaks - I got Tescon 1 tape to have a go at this one
Kitchen wastepipe ..easy fix with loadsa expandyfoam into gap, much of it going into cavity:-) I love expandy foam
Downstairs solid floor.. will use Unibond 3in1 sealant after varnishing the floor & repainting skirting
Little cracks under a few windowsills, fixed with sealant
Lofthatch needs more draughtproofing - I think a door style one, fitted from in the loft with hatch shut

Identifying a potential low-risk investment, I have bought up every second-hand Nissan 300zx z32 fairlady radiator fan labelled "Calsonic 9 Made in Japan" previously available on the internet. They are available direct from me at the very reasonable price of £10 each + £15 p&p.

Of if you see one of these parked in a back street and have a couple of 13mm spanners or sockets on you, then...http://en.wikipedia.org/wiki/Nissan_300ZX

The floorboards above our inset front doorway leaked a lot of air from the leak testing. Exploring(!) showed that there was a large void, of some 2m*1m*0.6m below the floorboards immediately over the front door.
So, I've filled this chock full of glass wool stuff. Then celotexed between the joists, then finished off with my favourite expandy foam and made airtight.

Exploring some more found that even though our cavity wall is filled (with glass wool 8 years ago), the cavity wall associated with the front door wasn't. Don't know why - maybe they thought we wouldn't like the holes drilled there? Maybe they forgot ? Maybe they knew that the top of this cavity had no cavity wall plate - (which it didn't)?
Anyway, taking matters into my own hands, I bought 3*100L bags of Silvapor, and poured it into the empty cavities. It went in a treat - piccy attached. Just took a coke bottle & cardboard tube to direct it into the right place, bag balanced precariously on the windowsill. As usual, wifey though I was nuts.

Only prob I can think of, is if we drilled a hole through the wall the silvapor would drain out again !

Full marks, reminds me of my lashed up warmcel blower, nice to know I'm not alone!

Have to ask how the toilet roll was incorporated into the work flow?

Something that occured to me whilst doing this, is why isn't this feature available on MVHR units designed for retrofit ? Or even new build ? They have massive fans that are capable of 50Pa at a decent flowrate, the fans have calibrated pressure/flow curves - so all that's required is pressure sensing & the ability to set both the in & the out fans to blow out, to depressurise a house. Then the occupant should check for leaks, or at least get a readout of pressure which will tell him how efficiently the system could operate. I'd go so far to say that this really ought to be done every so often on an MVHR enabled house. It must be so easy otherwise to have a leak, killing the system effiency. Having this test built into the MVHR would allow it at the touch of a button to check the system is performing as it used to, that you haven't left a window ajar somewhere. It's even a useful security check !

Maybe this is already done on some units? Manufacturers - you're free to use my idea !

Attached is a suitable sensor link, it's £73, but has a claimed repeatibility of 0.25Pa whilst my U pipe of water where 1mm=10Pa is say 5Pa repeatability if your eyes are good.
http://www.farnell.com/datasheets/327245.pdf

Ps - prev comments about wallpaper have been noted by Mrs RobL, who was & is itching to get it painted. I can't see the point myself, as it won't change the wall U value at all

Posted By: RobLwhy isn't this feature available on MVHR units designed for retrofit ? Or even new build ? They have massive fans that are capable of 50Pa at a decent flowrate, the fans have calibrated pressure/flow curves - so all that's required is pressure sensing & the ability to set both the in & the out fans to blow out, to depressurise a house.

That sounds like a good idea!

I will sometime lift a couple of floorboards at each of the gable ends - that will allow me to make all the joist ends and those breezeblocks airtight somehow. Thanks for the paint link ! I can't see me taking up all of the floorboards along the length of the house though - that would take ages & be very messy, especially as we have exposed floorboards.

I could bodge the box sections that I mentioned above (wall floorboard joist plasterboard making a 200mm*50mm void along the long lengths of the house)....check for cabling, if none then insert can of squirty foam into a few discrete holes in the floorboards...

Great stuff chaps! One question, I have this picture of you wandering around the house with a candle in hand to find the leaks. How did you really find them?

Opening myself up to a host of jokes now, but I've bought my own endoscope for the job...

My intention now is to drill holes every 4 or so floorboards, inspect for wires/whatever, then fill with foam if clear. I think I can push in and angle the nozzle so it fills the gap well. It will take a lot of foam - I think about 2dm*0.5dm*150dm = 150litres. A bit of dowling glued in will leave it looking neat.
Attached is standard piccy - top left block wall, lower right is the joist. There's not a lot of contrast in there, so it's hard to understand the pic. The movie is a lot easier.

Any foam recommendations?