Dear all,

Still insulating my cellar... but bathroom work is about to start. I've been looking at Single Room Heat Recovery Ventilator, SRHRV, or put more simply, a heat recovery extractor fan. I've got an old victorian house, can't fit a full house system, so a simple fan system seemed like a good idea.

Find below the products I found, searching quite hard! Why is it so hard to find this? Are they really too expensive for what they achieve? Is it really worth the £200 they seem to cost?

My house is leaky and that's not gonna change, the bathroom will have a big radiator/towel ladder on the opposite wall to the window (against bedroom wall), with thermostatic valve. Will this heat recovery fan really reduce the need for gas heating in that room?

I got the idea for this somewhere on this forum, whoever did it, is it working?

Thanks for any comments,
Thierry


---------------------------------------------------

HR25 or EC25

http://www.ecofirst.net/heat-recovery-ventilation.asp
Ecofirst Limited
They sent me a series of PDF for various products, all from Vent-Axia:
HR4 (commercial)
HR25 (suitable for a house, see product link lower down)
HR30W (big rectangular, says health care)
HR100S and 100W/WH (big rectangular, for bathroom/WC)
HR200WK (big rectangular, for kitchens)
HR300 (commercial)


http://bespoketesting.co.uk/baxi/products_ms_ec25.php
Baxi Clean Air
EC25, small "standard", strangely similar to HR25 from Vent-Axia.
Rest of the range (100, 200, 300) reminds me of the Vent-Axia models.


http://www.admsystems.co.uk/website_dec06/adm1.html
(Single room paragraph near the bottom)
They sent me an EC25 pdf brochure (from a bigger catalogue, section 2.1.3, dated september 2001)


http://www.vent-axia.com/products/vacas/hr25.asp
The actual Vent-Axia page with the whole range of HR25. Comparing the specs, and the technical drawings, I can tell that the EC or HR prefix mean something, but the actual product is the same.
Vent-Axia HR25 £186.40 ex VAT (pull cord)
Vent-Axia HR25H,L, LH,LP or P £205.72 ex VAT (various options, infra red sensor, humidity, etc...)

---------------------------------------------------

Xpelair XHR150

http://www.kair.co.uk/khrv150.htm
Manufacturer link.


http://www.applied-energy.com/en/xpelair/products/range/1908


http://www.kiltox.co.uk/khrv150eco.htm and
http://www.i-sells.co.uk
Online reseller for Kair. Don't really understand the differences, but one at £223 (for the /12RH) and the other at £283 ex VAT (for the /ECO, "enhanced version")

---------------------------------------------------

http://www.silavent.co.uk/products/heat_recovery/energex-features.asp
ENX 100 LV (low voltage for bathroom in my case).

-------------------------------------------------
Finally:
http://www.johnsonandstarleyltd.co.uk/ammend/prodvent.asp?p=single

-------------------------------------------------

Well yes, maybe no condensation, but I need a fan in the bathroom to remove air loaded with steam. A bathroom fan sucks the hot air out, straight to waste. The idea of heat exchanging is to heat the incoming air by transfering the heat from the outgoing air flow, to reduce the energy usage and bill. My question is, is it worth it/do these things work? rather than if I need a fan or not.

Cheers
T

<blockquote><cite>Posted By: gordon1001</cite>
Comments made at the following link suggest they are a waste of energy/money.

<a rel="nofollow" href="http://www.airtechenvironmental.co.uk/pages/pr05.html">http://www.airtechenvironmental.co.uk/pages/pr05.html</a></blockquote>

I just had a quick look at this site and saw that they were quoting the Met Office for an average UK windspeed of 5m/s. I very much doubt that is true for the average urban dwelling, so things may not be as bad as they make out, especially if the vent is at rt angles to prevailing direction. I'd still be a bit sceptical, though.

Ebay if you want cheaper. Ventaxia hr25 and a silavent model on at the moment.

thierry - many thanks for your list of links, it has saved me doing the research myself.

I'm less concerned about whether they are worth it, ie energy savings versus cost of unit and installation as to whether or not they work, ie extract the humidity without creating a ruddy cold draught. I'm sure it's one of the reasons many people suffer from mildew round the bathroom windows. They don't turn the extractor on because of the cold wind whistling round their nether regions when they have just got out of the shower. Do any of them heat up the incoming air supply sufficiently to avoid this problem?

I shall be in this exact boat later this year - in my case my bathroom doesn't leak air and my wife loves it big, deep, hot and steamy........(the bath, the bath!) and an ordinary extractor fan wouldn't do much in that situation unless the door was opened and then the effect would be rather lost, so it SEEMS like a good idea...most of all that lovely heat is saved but the air changes and the humidity therefore leaves. I fantasize about reading in a chaise lounge whilst other half relaxes so that is 2 reasons to get a solution!

So serious gratitude to you thierry for posting all your hard work; I can't afford a white elephant so PLEASE post your solution as and when the post dries up and/or you decide what to do. Most of all does anyone actually have experience of them - tony, is this technology really 25 years old and you are referring to one of the 'original' ones? A waiting room is as far from a relatively sealed room as it is possible to get inside so it would be great to hear from a SRHRV user.

Why can't you just use a couple of these in a PassiveHaus?

Take the mesh off? Replace with expanded metal, garden sieve or whatever - enough to keep birds and big bugs out. Or what about those solenoid operated flaps that look like little venetian blinds?

Posted By: Barnacle...I bought and installed a Vent Axia HR25 in my bathroom with the idea that it would get rid of the steamy air from baths/showers and retain some of the heat energy. It did not work - because the fan has a dust mesh over its outflow air vent that gets blocked up by the condensation, stopping the extraction side working

Just wondering if you've found a solution to your problem??? I've been weighing up the various different single room MVHR units on the market and the HR25 Solo Plus was my favourite. Until I saw your comments!

I'm looking to stomp a condensation problem in my bathroom, and am looking at the various units. Prices seem to vary widely, from about £170 for a Vent-Axia Tempra (which looks about the size of a refrigerator) up to £400-odd for one of the new Environvent Heat-Savas. A bit eye-watering, but I'm loathe to fit a cheap humidistat fan and just blow all the heat out the side of the house.

This thread is pretty old (arise from the grave!) and I was wondering if anyone had anything more recent to add? Seen a few people have fitted the HR25s, but what about other units? Effectiveness, noise, etc?

I have commented in several threads on the HR25, of which I have some. I have had problems with failures of the units - several times. However I believe that the motors now have a 5 year warranty, which they did not when I got mine. Nobody else on this site seems to have had problems with failures.

Are they expensive? Yes, but there does not appear to be anything cheaper. They also only consume 2W when not on boost, so v cheap to run.
Do they work? They certainly help a lot, although I too get rattles if it drops below -5 outside (presumably condensate freezing near the blades).

Just a simple volume control damper in the extract should allow you to create small differences in volume flow

regards

Barney

Posted By: RobinBDoes anyone know can any of these units be set to pull in slightly more air than they suck out?

you could link up the hr100 back to front and that would

The Retrovent looks to be pretty close to balanced input and output in trickle mode Hikersong. In boost mode it actually pulls in more air than it extracts. The Vent-Axia HR-25 might be a better bet for you, it extracts more than it inputs all the time.

If you want to encourage a bit of extra airflow across your stove you might want to look at one of those little Stirling engine fans that sits on top of the stove.

Another question which my wife has just asked. Again another one I didn't think about. In relation to room humidity will not the air I draw in (here on the humid west coast of Scotland) actually make the inside humidity worse?

Starting to think I might have made an expensive mistake.