Which MVHR?

[Novice]

I am trying to decide on which MVHR units to use in our new build passive house of 425m2. The units I am considering are the Airflow DV110 (2 units) or Renovent Excellent 300 (2 units).

 

Does anyone have any experience of these units and would value any feedback regarding sizing?

 

Both the quotes I have are supply only (but provide layout). I would need someone to install (don't have the time), who would install the system, plumber, electrician or a specialist?

 

Are there any firms that provide a commissioning service?

 

Many thanks.

[tonyshouse]

I went for Genvex, perfect apart from it won't talk to my home automation system

 

I think that you don't need anything like the number of air changes that are designed in. 

 

Watch out out for the cost of filters, we use very good ones so have lovely air quality 

[IanR]

2 hours ago, Novice said:

I am trying to decide on which MVHR units to use in our new build passive house of 425m2. The units I am considering are the Airflow DV110 (2 units) or Renovent Excellent 300 (2 units).

 

Do you know what volume your house is?

 

I've got a similar area and 2 DV110's wouldn't shift enough air, although I do have a proportionally large volume for my floor area.

 

I'm going with a single DV1100 unit. It's a small commercial unit, but still PH Certified.

 

I also found that some Airflow distributors have far better "terms" with Airflow than others. It pays to push Airflow on the RRP price of the designed system (Airflow dropped 18% on their original cost when pushed hard) and then shop around with the spec list to so who will do the best price on it (Travis Perkins got it down a further 7.5%). 

[le-cerveau]

Agree with IanR, I have a similar TIA and 437m2 and building regs gives me a rate 472.8m3/h.  the DV110 may say 414 m3/h but is only PH certified for 63-256 m3/h so would be running virtually flat out and increase your noise.  The Renovent says 300m3/h but PH of 59-235 m3/h so again flat out.  My suppliers recommendations and all advice from the collection on this and the previous forum have been to have the unit (s) running at approximately 50% maximum and the simple economies of scale tells you that one larger unit will be more efficient than 2 smaller units.  You may find that most suppliers will push you towards what they carry as standard rather that what is best for you.  For you ducting also consider being able adjust the flow control at the manifold as if you adjust at the inlet/exhaust valve that is where the noise will be generated. 

If you are looking for an install company then may I suggest look at the Irish market, they have a more advanced base than the UK.  (I can PM you who I am looking at)

[ragg987]

My installation was done by my builder, if I were do do it again I would employ a specialist. Most of the ducts were semi-rigid so that was fine, rigid ones were not simple to get done.

 

One large unit is not always going to be more energy efficient than 2 smaller ones. With 1 unit you may end up pushing air through very long ducts and will need a higher fan speed to overcome the increased resistance, whereas 2 smaller units could mean positioning each for shorter runs and reduced fan speed. (e.g. closer to either end of a long house).

 

I have no practical experience with 2 units, but would be concerned on how to balance the 2 given the house is a single volume. Also you have 2 inlets and outlets to take care of.

[Novice]

Total volume of house is 1086m3 @IanR

 

I agree with feedback and would like the unit to be running at 50% of capacity most of the time.

 

The suggested configuration is to have one unit for the ground floor with the second running the first floor. Does anyone here run a system in this way?

 

[Jayobn]

On 20/08/2016 at 13:10, ragg987 said:

My installation was done by my builder, if I were do do it again I would employ a specialist. Most of the ducts were semi-rigid so that was fine, rigid ones were not simple to get done.

 

One large unit is not always going to be more energy efficient than 2 smaller ones. With 1 unit you may end up pushing air through very long ducts and will need a higher fan speed to overcome the increased resistance, whereas 2 smaller units could mean positioning each for shorter runs and reduced fan speed. (e.g. closer to either end of a long house).

 

I have no practical experience with 2 units, but would be concerned on how to balance the 2 given the house is a single volume. Also you have 2 inlets and outlets to take care of.

Sorry for resurrecting an older thread, but I must agree with the comment about having a specialist install over a builder.  Of course you could install most of the system yourself too.  Whilst I'm certain there are some builders who can do this job competently,  those I have worked with fall way short of the mark.  Last year I resorted to refitting our system myself, and bringing in a bpec installer to do the bits I couldn't.

 

On 20/08/2016 at 13:10, ragg987 said:

My installation was done by my builder, if I were do do it again I would employ a specialist. Most of the ducts were semi-rigid so that was fine, rigid ones were not simple to get done.

 

One large unit is not always going to be more energy efficient than 2 smaller ones. With 1 unit you may end up pushing air through very long ducts and will need a higher fan speed to overcome the increased resistance, whereas 2 smaller units could mean positioning each for shorter runs and reduced fan speed. (e.g. closer to either end of a long house).

 

I have no practical experience with 2 units, but would be concerned on how to balance the 2 given the house is a single volume. Also you have 2 inlets and outlets to take care of.

 When I build my next home I will defiantly have it written into the contract that a specialist is to do the install!