Balancing MVHR

[Ambaz79]

Hello

 

Our Builder has installed an MVHR and I had some advice on designing the system on a different thread earlier in the year.  We have now moved in and are running the system on a general setting however none of the vents/extracts have been balanced.  I have borrowed the Anenometer but I cant get my head round the sheet and how to correlate this with the meter we have.  Is there anyway someone can help with this.  

 

Few points thats might be questioned on the design of the ducts.

 

1, Living room and supply and extract as we plan to have a Log Burner.

2, Temple Room - We do Diva's and Jot Sticks so I have added an extract above where this going to be to remove the smoke more than anything. 

3, House is divided into left and right via Manifolds on either side. 

4, System used here is the Holtop XHBQ-D10DMTHA (Its the factory that make the Mitsubishi Losnay MVHR).  

5, Ducting used is BPC's Quiet Vent Ducting and 4 of there 10 Spigot Manifolds.

5, on the drawing where I show the MVHR Duct positions I have labeled the positions with 2 if they have 2 x 75mm Rigid ducting running to them.  The rest just have a single pipe running to them. 

 

 

Happy to clarify if there are any other questions.

 

I just need to work out what I need to get the m/s to on the testo anenomter per room.

 

Thanks allot in advance! 

 

 

 

MVHR Room Size.xlsx Holtop Manual- XHBQ-DMTHA with touch screen controller (4).pdf

Edited October 25, 2023 by Ambaz79

[Deniance]

Any idea what the last collar is made of on the anemometer cone? I’ve got the 100 mm pipe and the bit that takes it to 125, and I’ve got the 125 to 150 collar, but need one more to make it a little bit bigger

[Ambaz79]

No idea sorry. I just got it like this. 

[Marvin]

Hi @Ambaz79

 

Will the log burner be room sealed?

 

[Marvin]

20 hours ago, Deniance said:

Any idea what the last collar is made of on the anemometer cone? I’ve got the 100 mm pipe and the bit that takes it to 125, and I’ve got the 125 to 150 collar, but need one more to make it a little bit bigger

Could try this

https://www.diy.com/departments/kair-ducting-reducer-200mm-to-150mm-8-to-6-inch-duct-pipe-reduction-connector-for-extract-fans-and-ventilation-units/5060272542092_BQ.prd

[Ambaz79]

9 minutes ago, Marvin said:

Hi @Ambaz79

 

Will the log burner be room sealed?

 

Hello, Not sealed but potentially door will be closed when Log burner is on. 

[JohnMo]

2 minutes ago, Ambaz79 said:

Hello, Not sealed but potentially door will be closed when Log burner is on. 

 

Depending on your airtightness then, you will need a full time (cannot be opened or closed) ventilation source in the same room as the log burner. Building regs give the criteria and size. Pretty sure your mechanical ventilation doesn't count as ventilation for a non room sealed stove.

 

I pretty much say having a supply and extract in the same room is not the best move.  If you have your fire on and the room is otherwise quite airtight you could start to comprise the fires seals and the chimney effect and start letting smoke into the room. As the fire and the extract will be depressurising the room. I would go further to say unless you address it now - quite dangerous.

 

22 hours ago, Ambaz79 said:

 

1, Living room and supply and extract as we plan to have a Log Burner

 

If you haven't bought your stove, get a room sealed one where primary and secondary air are taken from outside.

[Ambaz79]

Hello,  Sorry I thought you were asking if the room is sealed (sorry my bad).  We have not purchased the burner yet and I have in mind this needs the air from outside and would be sealed.  

 

The house is pretty airtight however has been built in the traditional block and block form with 100MM Celotex thats taped.  Windows are triple glazed with no trickle vents and door has no letter box (All Imported from Poland). So its not completely airtight to a professional level however where I can I have sealed the gaps. Hope that makes sense. 

 

 

[Deniance]

3 hours ago, Marvin said:

Could try this

https://www.diy.com/departments/kair-ducting-reducer-200mm-to-150mm-8-to-6-inch-duct-pipe-reduction-connector-for-extract-fans-and-ventilation-units/5060272542092_BQ.prd

Just the ticket, sure as hell ain’t paying a tenner for it though! I’ll check Amazon cheers 

[Adrian Walker]

On 25/10/2023 at 14:01, Ambaz79 said:

Hello

 

Our Builder has installed an MVHR and I had some advice on designing the system on a different thread earlier in the year.  We have now moved in and are running the system on a general setting however none of the vents/extracts have been balanced.  I have borrowed the Anenometer but I cant get my head round the sheet and how to correlate this with the meter we have.  Is there anyway someone can help with this.  

 

Few points thats might be questioned on the design of the ducts.

 

1, Living room and supply and extract as we plan to have a Log Burner.

2, Temple Room - We do Diva's and Jot Sticks so I have added an extract above where this going to be to remove the smoke more than anything. 

3, House is divided into left and right via Manifolds on either side. 

4, System used here is the Holtop XHBQ-D10DMTHA (Its the factory that make the Mitsubishi Losnay MVHR).  

5, Ducting used is BPC's Quiet Vent Ducting and 4 of there 10 Spigot Manifolds.

5, on the drawing where I show the MVHR Duct positions I have labeled the positions with 2 if they have 2 x 75mm Rigid ducting running to them.  The rest just have a single pipe running to them. 

 

 

Happy to clarify if there are any other questions.

 

I just need to work out what I need to get the m/s to on the testo anenomter per room.

 

Thanks allot in advance! 

 

 

 

MVHR Room Size.xlsx 12.96 kB · 1 download Holtop Manual- XHBQ-DMTHA with touch screen controller (4).pdf 1.72 MB · 0 downloads

 

 

Jeremy, who used to be on here, has excellent notes and a spreadsheet that will help you achieve a well-balanced system, which I have used several times with great success.  I will have a hunt for them and post later. I suggest that you use a CO2 monitor at the same time to check that the airflow is high enough. The formula you need is Flow Velocity (m/s)  x   Pipe Area  =  Flow Rate (l/s)

 

 

[Adrian Walker]

On 25/10/2023 at 14:01, Ambaz79 said:

Hello

 

Our Builder has installed an MVHR and I had some advice on designing the system on a different thread earlier in the year.  We have now moved in and are running the system on a general setting however none of the vents/extracts have been balanced.  I have borrowed the Anenometer but I cant get my head round the sheet and how to correlate this with the meter we have.  Is there anyway someone can help with this.  

 

Few points thats might be questioned on the design of the ducts.

 

1, Living room and supply and extract as we plan to have a Log Burner.

2, Temple Room - We do Diva's and Jot Sticks so I have added an extract above where this going to be to remove the smoke more than anything. 

3, House is divided into left and right via Manifolds on either side. 

4, System used here is the Holtop XHBQ-D10DMTHA (Its the factory that make the Mitsubishi Losnay MVHR).  

5, Ducting used is BPC's Quiet Vent Ducting and 4 of there 10 Spigot Manifolds.

5, on the drawing where I show the MVHR Duct positions I have labeled the positions with 2 if they have 2 x 75mm Rigid ducting running to them.  The rest just have a single pipe running to them. 

 

 

Happy to clarify if there are any other questions.

 

I just need to work out what I need to get the m/s to on the testo anenomter per room.

 

Thanks allot in advance! 

 

 

 

MVHR Room Size.xlsx 12.96 kB · 1 download Holtop Manual- XHBQ-DMTHA with touch screen controller (4).pdf 1.72 MB · 0 downloads

 

 

Jeremy, who used to be on here, has excellent notes and a spreadsheet that will help you achieve a well-balanced system, which I have used several times with great success.  I will have a hunt for them and post later. I suggest that you use a Co2 monitor at the same time to check that the air flow is high enough. There are no flow rate calculations in your spreadsheet

 

 

[Ambaz79]

In all honesty I am a bit lost with this.  Apart from what I have sent across in the oiginal post I dont have anything else.  I thought with the above info someone should have some sheet that could work the rest out once the room sizes are inputted.  I could be wrong though! 

[JohnMo]

Basically you are seeming to over complicate.

 

Room size makes no real difference to much, it the overall house size and room function that dictate flow rates. This will give you a starter. But look at current building regs also. Plus if it's getting signed of you will need a certificate of calibration for the flow meter. Inward and outward flow need to match also.

 

But clear how you designed the system with no clue on your target flow rates?

 

[Ambaz79]

Hi @JohnMo Yes to be honest it was a bit of a DIY attempt and although I did get allot of advice from the forum aswell as the factroy who supplied the unit I would agree its not been designed to a specific standard.  I dont need any certificates as the house is already signed off and there was no requirements for me to provide any certificate of caliberation. I just need to get the system set so the house is comfortable and healthy to live in. 

 

So if I look at the table you have sent then I would go with the 4B'rm./ 5P: 90m3/h [25 l/s] and set the extract as mentioned in the table too.  

 

How do I acheive the air exchange rate?  how does this effect the calculations above? Also is the Air Exchange rate actually set at the supply and extract that is measured directly from the actual MVHR Inlet and outlet.  The house is around 400 M2. 

 

Your right I could be overcomlicating this! 

 

 

[JohnMo]

So using passivhaus or English rules the ventilation rate is around 400m3/h, from the bottom row on the table. But really depending on how many people are in the house, that could be over ventilated in reality, so the 4br/5p at 90m3 or somewhere in between.

 

Your trouble is the amount extracts you have and if you do the passivhaus rates for those that are actually wet rooms,

 

3 x shower rooms at 31m/h

1 x Kitchen at 46m3/h

1 x Utility at 15m3/h

 

So already at 156m3/h, plus you still have a further 4 extract points to consider. Pantry and kitchen do those to match the kitchen rate between them so say 10m3 in the pantry the rest in the kitchen, plant room as small a flow as you get. Temple a low nominal number.

 

You then need to match the supplies to an equal extract flow rate overall. Basically the more people you are likely to have in a room the higher flow required. I do a quite high flow in a lounge, a low flow in a single bedroom, big areas where very little happens day to day, a low nominal flow.