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22 hours ago, PeterStarck said:

I bought one of those and it's still sitting in it's box unused. 

 

snap, so did i, it’s on my very long “to do list”. Frankly it’s been so warm here fir months and the wife and I like the windows open I turned the MVHR off. Yesterday to balance the MVHR as well!

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30 minutes ago, PeterW said:

So why bother ...??

Because sometimes you DO notice something which may justify the price difference . Between just about any MVHR system costing 600 quid and another twice the cost it’s hard to tell . That’s why I did the post ; too see if anyone jumped in with a valid reason to choose one over the other .

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More thoughts ...

The in/out air pipes .

I want to mount them on the external wall as roof would be a pita .

Is it not unreasonable to cut out a slot in the insulation between the rafters and run the pipe either down into the cavity wall or to the eaves ? ( assuming it will fit ) 

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2 hours ago, pocster said:

More thoughts ...

The in/out air pipes .

I want to mount them on the external wall as roof would be a pita .

Is it not unreasonable to cut out a slot in the insulation between the rafters and run the pipe either down into the cavity wall or to the eaves ? ( assuming it will fit ) 

 

The inlet and exhaust ducts will be at least 150mm in diameter, and need to be spaced apart on the wall by a couple of metres, so that may have a bearing on where you fit them.  Best have both of them on the same wall, as I didn't take heed of this and as a consequence our MVHR gets unbalanced if we get a strong wind from the West or East.

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5 minutes ago, JSHarris said:

 

The inlet and exhaust ducts will be at least 150mm in diameter, and need to be spaced apart on the wall by a couple of metres, so that may have a bearing on where you fit them.  Best have both of them on the same wall, as I didn't take heed of this and as a consequence our MVHR gets unbalanced if we get a strong wind from the West or East.

150 ? Oh ! I thought they’d be the same as the ducting I.e 75mm 

Wall then - going to be tricky getting them in a TF and ( as my trusses are high ) in the wall section ?

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  • 2 weeks later...
On 01/07/2019 at 07:16, JSHarris said:

The programmable humidity sensor and switch I used was this unit from Poland: https://www.ebay.co.uk/itm/DHC-100-Feuchtigkeitsregler-Hygrostat-Humidity-Control-Sensor-Fuhler-2-meter/182951476628?hash=item2a98c1fd94:g:hAgAAOSwFSxaKeA~

 

I put the remote sensor inside the extract plenum chamber and it seems to work well.  Boost turns on within a few seconds of a shower starting, or even just from the steam from making a cup of tea, and the unit can be programmed with a variable turn off delay and RH hysteresis.  I fitted the controller inside a surface mount box, in the services room, just above the MVHR:

 

5746b02169028_Humiditycontroller2.thumb.JPG.eca97a7fd0f95b80521aee98564b374f.JPG

About to p/board in my main service run and keep wondering whether I need to put in humidity switches in the bathrooms before doing so. I know most people say they do not bother with them but I notice you have a sensor adjacent to the MVHR unit and I wondered if this could be retro fitted in the future if I decide we need one and not bother with individual bathroom switches? TIA

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27 minutes ago, Pete said:

About to p/board in my main service run and keep wondering whether I need to put in humidity switches in the bathrooms before doing so. I know most people say they do not bother with them but I notice you have a sensor adjacent to the MVHR unit and I wondered if this could be retro fitted in the future if I decide we need one and not bother with individual bathroom switches? TIA

 

I retro fitted the one pictured, I just put the remote sensor that comes with that unit inside the extract plenum chamber, which is fairly close to the MVHR unit.  The MVHR just needs a dry contact switch to make it boost, and this humidity controller has dry contact relay contacts available.  It should work with any MVHR that has a switch input for boost.

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On 02/07/2019 at 18:46, JSHarris said:

 

The inlet and exhaust ducts will be at least 150mm in diameter, and need to be spaced apart on the wall by a couple of metres, so that may have a bearing on where you fit them.  Best have both of them on the same wall, as I didn't take heed of this and as a consequence our MVHR gets unbalanced if we get a strong wind from the West or East.

 

If space is really limited you can put the ducts much closer together using a combined grille like the Maico KWH 16 R

http://www.heatspaceandlight.com/space-mvhr-ducts-tight-combined-intake-exhaust-grille-solution/

 

Only know this because our system designer has suggested this. He's also recommended the enthalpy exchanger too (partly because we may add some active heating via the ducts, which can push humidity even lower)

 

 

Edited by joth
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2 hours ago, joth said:

 

If space is really limited you can put the ducts much closer together using a combined grille like the Maico KWH 16 R

http://www.heatspaceandlight.com/space-mvhr-ducts-tight-combined-intake-exhaust-grille-solution/maico-combined-exhaust-intake-grille-for-mvhr-ventilation-systems/

 

Only know this because our system designer has suggested this. He's also recommended the enthalpy exchanger too (partly because we may add some active heating via the ducts, which can push humidity even lower)

 

 

 

I'd only consider that in a really extreme set of circumstances, as there will inevitably be some degree of mixing between the intake and exhaust, plus it may well invalidate some performance elements of the MVHR unit warranty, or be considered non-compliant by building control if they chose to be pedantic.  It's a compromise solution, for circumstances where it would be impossible to fit two well-separated external terminals, rather than something to be used routinely.  There is guidance in Part F and in the associated Domestic Ventilation Compliance Guide on the placement of fresh air intakes and exhaust terminals and it states that the exhaust terminal should be positioned down wind (relative to the prevailing wind conditions) from the intake, and sufficiently far away from it to ensure that exhaust air is not drawn in to the intake. 

 

Additionally, MVHR manufacturers often stipulate in their MIs the spacing, and MIs always overrule building regs when it comes to compliance demonstration.  For example, the MIs for our MVHR stipulate the following separation criteria between intake and exhaust:

 

image.png.bfe8e31c55132634ada9355853754424.png

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2 hours ago, JSHarris said:

it may well invalidate some performance elements of the MVHR unit warranty, or be considered non-compliant by building control if they chose to be pedantic. 

 

The link I posted was a bit duff (now edited), I meant to get the blog article + comments that do touch on Building regs (in a non-conclusive way)

http://www.heatspaceandlight.com/space-mvhr-ducts-tight-combined-intake-exhaust-grille-solution/

 

This is a good point though, if it comes to aesthetics vs performance+compliance, then the aesthetics can certainly give a bit (conservation area be damned!)

Thanks!

 

Edited by joth
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We are back too.  The ferry spat us out at 7AM this morning at Aberdeen after a dead calm crossing.  And at that time on a Sunday morning the A96 is a delight to drive along.

 

The two ladies of the house seem to have an inability to sleep on boats or planes, and have both gone to bed to catch up.

 

I need to get the lawnmower out, our flat lawn resembles a wild meadow just now.

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17 minutes ago, ProDave said:

 

I need to get the lawnmower out, our flat lawn resembles a wild meadow just now.

 

I'm interested, is the new house soundproof (& vibration proof?) enough that your mowing ths lawn won't wake them up?

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On 01/07/2019 at 16:46, PeterStarck said:

I bought one of those and it's still sitting in it's box unused. I have never found it necessary to increase the extract fan speed.

 

Same with me.

 

3.5 years of leaving it on the low setting, and zero issues with moisture. Bathrooms are always completely dry within hours.

 

I only use the boost if I'm cooking something likely to set off the fire alarm (eg, steak cooked on a hot griddle).

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8 hours ago, Oz07 said:

Why do bpc quote on two different types of ducting? What's so good about red one?

The red stuff is slightly more flexible than the blue. They've both got the smooth white interior.

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