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2 hours ago, Adsibob said:

Thanks @troggy02 thats v helpful. What make and model unit do you have and who did the install and design?

 

It's a Vent Axia sentinel kinetic plus. With what I know now and given the choice I would have gone for the LO-CARBON SENTINEL KINETIC ADVANCE which is more expensive, but I like the idea of wifi access to it.

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19 minutes ago, troggy02 said:

It's a Vent Axia sentinel kinetic plus. With what I know now and given the choice I would have gone for the LO-CARBON SENTINEL KINETIC ADVANCE which is more expensive, but I like the idea of wifi access to it.

To do what with it. Turn it on and leave it on. Every 6/12 months depending on how dirty your filters get turn it off and change them. Turn it back on and forget about it till they need changed again. It's not a tech item to play with and adjust. Fit and forget.

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1 minute ago, Declan52 said:

To do what with it. Turn it on and leave it on. Every 6/12 months depending on how dirty your filters get turn it off and change them. Turn it back on and forget about it till they need changed again. It's not a tech item to play with and adjust. Fit and forget.

Don’t you toggle the boost switch every so often or is that all automated? What about at night when you want it to run more quietly?

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Just now, Adsibob said:

Don’t you toggle the boost switch every so often or is that all automated? What about at night when you want it to run more quietly?

Nope. It works away on its own. It's silent so can't hear it working away. It's a low powered fan so shouldn't be noisy. It's not like having an kitchen extractor fan going flat out. 

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19 minutes ago, Declan52 said:

To do what with it. Turn it on and leave it on. Every 6/12 months depending on how dirty your filters get turn it off and change them. Turn it back on and forget about it till they need changed again. It's not a tech item to play with and adjust. Fit and forget.

 

For me it's a tech item to play with 😀. The filters definitely definitely don't last more than 6 months, they're pretty black by then. There are times when it's useful to boost the circulation, smelly cooking for example. Currently activating boost requires me to crawl in to the cupboard and press the button. Even if it didn't, the units on the 3rd floor and kitchen on the ground. Yes, I could get an extended display but don't you think an app is do much cooler!

 

Seriously though, I like to know what the bypass is doing and what it thinks the internal and external temperatures are. Partly this is because I'm not convinced it's working as designed. Once it's switched in to overnight bypass it should switch back to normal once the internal temp hits the set point, but ours continues until it's hit the time limit before finally switching. I had a case open with Vent Axia last year, but then the weather cooled and I was not able to diagnose any further.

Edited by troggy02

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👍 to Declan's comment.  We have a reasonably spec'ed passive-class house with a Vent Axia MVHR system that's been running for over 3½ years.  Pre moving in, I looked at all sorts of options control bypass, etc. by my RPi-based home automation system, but the reality is that we just leave it running and forget about it  -- apart from swapping out the filters ever 4-6 months.  I do press the boost button occasionally if we've been doing frying etc. that overloads the recycling cooker hood, but that's about it.  We also open windows in the summer on occasion, but just leave it running.  It works.  It costs almost nothing to run.  The house always smells fresh.  It reduces air-circulation-related heating costs by ~90%  -- and that drops my heating demand in winter by maybe 30-40%.   What more is there to say.

Edited by TerryE
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I added a Pi-based controller as I was finding the built-in humidity trigger to be a bit hit and miss. The threshold was set on the unit but it was an absolute threshold so just when I got the balance right it'd need tweaking as the seasons changed. Sometimes it wouldn't trigger when I expected it to and sometimes it'd do so when I didn't. 

 

As I had an unused Pi Zero and humidity sensor I put it to use even if it was a bit overkill. To lessen this though I add temperature sensors to the four main ducts so I could monitor (and graph) its performance. Useful to begin with when I was still learning about MVHR, and I still look at it occasionally now. Handy for knowing the outside temperature too, and I've always liked graphs. 😉 I may expand it to have greater control over the summer bypass and summer boost if I get some time to do so. 

Edited by MJNewton
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2 minutes ago, MJNewton said:

Handy for knowing the outside temperature to

It is a good place to monitor the outside temperature as it is unaffected by sun direction.

 

I have Temp and RH sensors in @joe90's MVHR, but he has not balanced it yet, and turns it off sometimes.

 

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5 minutes ago, SteamyTea said:

and turns it off sometimes

Only in hot summer weather (when er indoors has all the windows open).

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12 minutes ago, MJNewton said:

As I had an unused Pi Zero and humidity sensor I put it to use

 

(I forgot to add...) 

 

... as a rate-of-rise humidity sensor so it boosts on a >5% rise in 5 minutes. 

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2 minutes ago, MJNewton said:

as a rate-of-rise humidity sensor so it boosts on a >5% rise in 5 minutes. 

 

Ah, this is what i wanted, my RH varies a lot  and I can’t find a setting for my humidistat that covers different weather conditions. Can someone point me (a Luddite) at a humidistat that works on rise of RH, not a set level.

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6 minutes ago, joe90 said:

Can someone point me (a Luddite) at a humidistat that works on rise of RH, not a set level.

Someone made on on here, can't remember who it was, but it is basically fairly simple to do.

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44 minutes ago, SteamyTea said:

fairly simple to do.

Fir you maybe!!, can anyone post a source or diagram (I can solder).

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1 hour ago, joe90 said:

can anyone post a source or diagram (I can solder)

It is the programming that is the tricky bit if you have never down it before.

 

 

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On 31/01/2021 at 10:01, MJNewton said:

Handy for knowing the outside temperature too,

 

I use the Metoffice for that 😊

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10 hours ago, TerryE said:

I use the Metoffice for that

What happens when you loose connectivity?

 

 

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@SteamyTea, Nick my NodeRED system does a RESTFul API call every day just before Midnight and writes the value to a MySQL table.  The system then fetches the latest reading. Yes, I do get the occasional timeout, but this defaults to the previous day's reading.  No big deal.  It did fail a week ago because they have a just over 3 year validity for the API key.  I forgot and it lapsed.  Oops.

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My preference for a 'real' outside temperature was just an issue of accuracy as my nearest weather station is around 10 miles away and any discrepancies could really throw out my calculations of heat exchanger efficiency/performance. 

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My nearest Metoffice station is reasonably close, but as it is so cheap to add an external temp/RH/air pressure sensor, it would seem silly not to.

I like the idea of using others data, especially if it is prediction of the next days weather, but I am sure that can be worked out well enough locally (my cheap weather station calculates the sky conditions from just temp, RH and pressure, and is amazingly accurate.  I wish I knew the algorithm then used, but never managed to find it.

Knowing the weather for the next day would be useful as I am on E7, and down here the temperature can change rapidly in a few hours.

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On 18/12/2019 at 21:54, Thedreamer said:

I watched some videos on MVHR recently and wondered whether the ducting ever gets mouldy?

 

 

It should not purely on the basis that the ducts have air constantly moving through them.  Obviously the 'sucking' vents will regularly have damp air from showers/baths, cooking (and maybe clothes drying) entering them but this would normally only be for an hour or so a day and the rest of the time the air would be much drier.  I suppose also that the ducts most likely to get mouldy would be the sucking ones in which case any smell would be removed along with the damp air.

I had MVHR in my 5 bed house in E Herts for 10 years before I sold it and the only mould I ever came across was on the heat exchanger 'cube' inside the main box.... which is why they need washing once a year or so with bleach-basd cleaning medium.

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On 18/12/2019 at 20:59, DavidHughes said:

Well, having found this forum a few months ago and benefited greatly from the well-informed posts concerning MVHR...

 

Sorry, but to my (engineer's) mind, spending what might be a great deal of money on high performance double (or even tripple)-glazed windows only to bang a load of holes straight through the frames is perfectly insane.

If you are on a very tight new-build budget you are probably right and it might not be worth it but if you have an air-tight house (and have paid significantly for the privilege) MV is absolutely essential and if you are going to do that then adding the HR is not going to add hugely to the cost so you might as well have it, too.

For old masonry-built properties *undergoing extensive renovation* MVHR (or the MV side at least) is 100% worth it just to deal with issues of damp ingress through dodgy walls and foundations, particularly if some idiot has clarted the outside with cementitious render (and/or non-breathable paint).

Those of us who live near busy roads would also benefit hugely from MV for air quality and noise abatement issues (not having to have trickle vents).

Installation is certainly DIY-able which should keep the cost under £1k for a small house.

 

I would *strongly recommend* anyone who buys an MVHR unit gets one with 'summer by-pass' otherwise you will still be recovering heat from your expelled air in the middle of summer and warming incoming fresh air making the inside of the house unnecessarily warm.

In general, I could not disagree with you more!

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On 18/12/2019 at 21:11, ProDave said:

"I paid a lot less than you for my kit, I got the mvhr unit from ebay..."  

 

Which one?

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1 minute ago, martinwinlow said:

Which one?

We both got a kingspan lossnay unit after Kingspan pulled out of supplying them.

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