Iceverge

How do I approximate my MVHR efficency?

Recommended Posts

As per the title, I'm curious to find out the actual efficiency.

 

In use I have measured the supply temperature at 20.7deg and extract at 21.1deg. 

 

Flow rate is approx 100m3/hr. 

 

Is this enough information or do I need exhaust and intake temp too? 

 

It's a counter flow heat exchanger. I don't know the pressure drop across the unit or ducting. 

Edited by Iceverge

Share this post


Link to post
Share on other sites
40 minutes ago, Iceverge said:

Is this enough information or do I need exhaust and intake temp too? 

 

You would need the exhaust and intake temperatures, but there are  at least two additional problems, 1) The volumes of the two flows will probably not be the exactly the same, and 2) The heat from the fan motors will be added to the airstreams.

Edited by A_L

Share this post


Link to post
Share on other sites

Is it unrealistic to expect to calculate an overall efficiency in that case using only a cheapo anemometer/thermometer. 

7147XYppVRL._AC_SL1500_.jpg

Share this post


Link to post
Share on other sites
2 hours ago, Iceverge said:

Is it unrealistic to expect to calculate an overall efficiency in that case using only a cheapo anemometer/thermometer. 

 

IMHO, yes. The problem will be balancing and measuring the airflow. Any condensing in the heat exchanger would be an added complication.

 

If you do not have it you may find information on your MVHR in this database

 

https://www.ncm-pcdb.org.uk/sap/pcdbsearch.jsp?pid=34

Share this post


Link to post
Share on other sites

Right, that's firmly into the couldn't be arsed bin. 

 

I have the passivhaus cert and the DEAP (Irish SAP) cert but I was just curious. 

Share this post


Link to post
Share on other sites

For an approximate idea of unit operating efficiency (in terms of heat recovery - is that what you're interested in?) you can simply do (supply - intake) / (extract - intake). More accurate calculations described here.

Edited by MJNewton

Share this post


Link to post
Share on other sites

Ok, I'm enthused again.  Off to do some measuring. Will report back.  

  • Haha 1

Share this post


Link to post
Share on other sites
2 minutes ago, Iceverge said:

Ok, I'm enthused again.  Off to do some measuring. Will report back.  

You can use an IR thermometer if your aim is good.

Share this post


Link to post
Share on other sites

I have measured and discovered that my measuring apparatus is banjaxed. Inside temp 20 deg. Exhaust temp 20 deg. Inlet temp 20 deg. Outside temp 20 deg, in Ireland, in the night, in October. Lol.  

 

7 minutes ago, SteamyTea said:

You can use an IR thermometer if your aim is good.

 

I must make a purchase. 

 

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now