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Ventilation Boost switches

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Like quite a few others here, I bought my MVHR and ducting from BPC.  As part of their package they supplied two ventilation boost rocker switches, to allow remote boost activation of the MVHR.  Having left in drawstrings for cables, I'm now at the point of deciding whether to bother with these switches at all, as I can program a timed boost to the ventilation rate to coincide with morning showers (this is in addition to the inbuilt humidity sensor), and I will always have the ability to boost ventilation rates from the master controller which will be located centrally in the house.

 

Firstly, just looking for any feedback, good or bad about the switches and whether those who have installed feel they are worthwhile.

 

Secondly, on an installation note, BPC instructions indicate a 1mm 3 core cable from switch back to the MVHR unit.  Which terminal connection on the unit did you use to connect these switches?

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Another BPC customer here, we wired the MVHR boost function (sentinel Kinentic +) to activation of bathroom light switches and also put a PIR in for daytime activation.

 

These also activate the secondary return pump for DHW.

 

So we had no need for the switches.

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On 27 January 2017 at 20:11, Bitpipe said:

Another BPC customer here, we wired the MVHR boost function (sentinel Kinentic +) to activation of bathroom light switches and also put a PIR in for daytime activation.

 

These also activate the secondary return pump for DHW.

 

So we had no need for the switches.

 

Doing first fix wiring now and working out how best to control MVHR boost. How are you finding it working off the PIR and light switches? 

 

As an aside, when in boost mode, is the system any noisier in the rooms with inlets? Thinking specifically of bedrooms

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Boost airflow is marginally noiser - you actually only really notice when it switches off if that makes sense.

 

Not sure how the electrician wired up all of the PIRs and light switches to activate boost (and also the secondary pump, both work off the same switched live), but can ask him.

 

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Thanks :)

 

Do you have a boost function in all locations that have an extract or just the bathrooms?

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Late to this thread (must have missed it first time around)

 

I don't like the idea of a rocker switch. To me that means you turn it to boost and then later turn it back to normal.

 

I am planning to have in the kitchen, and next to the bathrooms a timed "boost" switch, probably thinking along the lines of the Horstman immersion heater boost switches where you can typically boost if from 15 minutes to over an hour in steps.  This will need a relay or two to interface it with the mvhr.  but I like the idea of push the button get in the shower and forget it. Some time later it will switch itself back to normal.

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Do I assume the mechanism for these boost switches is a simple volt free NO/NC type setup?

 

Just thinking I might link mine to my c-bus lighting setup. That way I can add some simple intelligence using PIR's etc.

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2 hours ago, worldwidewebs said:

Thanks :)

 

Do you have a boost function in all locations that have an extract or just the bathrooms?

 

We have the 'auto boost' in the 4 bathrooms and the MVHR controller, which has a boost function, in the utility.

 

Our cooker hood is not compatible with the cooker hood mode of the MVHR so theres a plan to put a current sensor on the supply for that to work.

 

On our MVHR, any boost signal runs the boost for 10 mins, you can't turn it off.

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We have two timed switches, one in kitchen and one in the Not Hot Press near the bathroom.  These are switches that can be adjusted to be "on" for between 20-120 mins, I got these in error as meant to buy the 2-20 minute version.

so before you go for a shower or are cooking we hit the boost button.

i have a humidistat on the MVHR and just haven't found it to work well.

when I try and adjust it to run when the shower is on (bathroom extract above shower on wall about 3m off ground) it just runs all the time - maybe I didn't spend enough time setting it finely enough but the boost button is just not a hassle and life's too short to mess around with something like that.

Didnt want it set to a light switch or a pir as it only needs to come on when the shower is on or if someone is cooking 

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Here comes the science bit....

 

"The switches and PIRs are basically just wired in parallel, the boost connections only usually give you the switching pair but the PIRs require a neutral so picked that up from the MVHR unit and then wired the whole lot by daisy chaining between each point with 3 core & earth with the neutral just connected through (separately to the local lighting neutral to avoid RCD tripping) in each conventional switch. The switches are double pole switches so that the local light switching is in one side of the switch and the MVHR boost in the other"

 

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The Timeguard PIR switches from TLC allow you to remove the factory link and become volt free if you have a need for that on your MVHR. 

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Worth noting that some MVHR units (like ours) use an isolated dry contact boost switch, so must not be connected to one side of a mains switch.  IIRC, the dry contact connection on ours is between the internal 0V rail (connected to earth) and a sense supply that's very low current at 24V DC.  That DC supply also runs the control unit, which is an ELV bit of kit, so again there is a safety risk if a combined switching system is used, as there needs to be isolation.

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Jeremy, have you fitted boost switches or do you rely on a humidistat sensor ?

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Giving this thread a bump.

 

My bathrooms and downstairs loo have a switch next to the light switch, on the same face plate, that is to allow a timed boost to the MVHR to extract any overly pungent smells after the deed has been done.  Although the switches are there (they are rocker switches, I believe) there is no circuitry to link and tell the MVHR system what to do.  What should I be looking for to put this right rather than have redundant and confusing switches?  Is there a proprietary box of tricks that can be purchased?

 

Thanks.

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13 minutes ago, vivienz said:

Giving this thread a bump.

 

My bathrooms and downstairs loo have a switch next to the light switch, on the same face plate, that is to allow a timed boost to the MVHR to extract any overly pungent smells after the deed has been done.  Although the switches are there (they are rocker switches, I believe) there is no circuitry to link and tell the MVHR system what to do.  What should I be looking for to put this right rather than have redundant and confusing switches?  Is there a proprietary box of tricks that can be purchased?

 

Thanks.

 

The answer will in part depend on the make/model of your MVHR unit. As an example I have an Airflow Androit unit. The "boost" is controlled by a volt free normally open circuit. 

Thus a "bell press" type switch will activate the boost.

 

As I mentioned above I linked mine to my lighting system. A second button in my bathrooms is programmed as a bell press and activates a relay which closes the circuit. 

 

 

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My unit is an ecocent from earthsave products; other than that, I can't tell you much about it, I'm afraid.

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Posted (edited)

Oh you might have an exhaust-air heat pump in your MVHR!

 

This one https://www.earthsaveproducts.com/products/mvhr-including-built-in-heat-pump/ecocent-air-mvhr. There is a link to the manual on the web page. Unfortunately, the manual does not seem to mention the word "boost".

 

If that is your model, you might be interested to know that both @Mikey_1980 and @dogman have the same one.

Edited by Dreadnaught
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Ah, thanks.  It seems that I have some redundant switches, then.

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