Single-Room MVHR - Any Thoughts Please

[GraHal]

Anybody got any thoughts on single-room MVHR or even anybody currently using?

 

I have checked a few, one with ceramic heat exchanger and one with alumininium, otherwise they look same / very similar. I noted that the manufacturers don't quote a % for heat transfer outgoing to incoming air.

 

Both above are quoted as 70 seconds extract, followed by 70 seconds fresh air in ... in and out down the same pipe.    Others I've looked at, use a balanced flue (concentric pipes etc).

 

Even if you are not using or not read up on them, any thoughts much appreciated.

 

Thank YOu 

[Marvin]

Hi @GraHal

 

In my humble opinion, I would want one with 2 pipes (an inlet and an outlet) or with a concentric pipe.

 

Our MVHR whole house system runs the warm air out, heating one side of a temperature transfer thing, whilst the fresh air coming in picks up the heat from the orherside of the temperature transfer thing at the same time. This warms the incoming air in winter.

 

Although it may be the single ones your looking at operate differently.

 

Can you post a link?

 

M

[jack]

5 minutes ago, Marvin said:

Although it may be the single ones your looking at operate differently.

 

They work on the same principle as a regenerator in a Stirling engine. Warmer air going through in one direction gives some of its heat to a thermal material, then the airflow is reversed and colder incoming air picks up heat from the thermal material, then the cyle is reversed again (etc).

[GraHal]

Thanks for both comments.

 

Here are links to the 2 I refer to in my OP.

 

https://www.ventilationland.co.uk/product/40954/decentralised-mvhr-unit-o100-mm-with-switch.html?utm_source=googleshoppingUK&utm_campaign=googleshopping-FeedUK&gclid=Cj0KCQiAic6eBhCoARIsANlox84gylzZ_oX2xqCYtogoCV8A0GZ1TTf19gNq_mMdtHpwf4c6Hu03sEkaAqhUEALw_wcB

 

https://www.ebay.co.uk/itm/322917943393

 

[HughF]

Partel lunos - very expensive but appear to be premium 

 

Prana recouperator - middle of the road 

 

Then there is the £149 one from ventilation land…

 

Mitsubishi make a nice looking one, the lossnay system. Looks like the inside unit of a mini split 

[Miek]

These units are not counterflow heat exchangers so are far less efficient at recovering heat.  If you think about the cycle,  as soon as the fan reverses, cold air starts to cool the core and carry the heat indoors, the more cold air passes over the core the more heat it looses until its as cold as the outside air temperature , then its just blowing in cold air. They are better than an extractor fan but nowhere near the efficiency of a counterflow heat exchanger. 

 

I have a vent axia single room heat recovery extractor fan, its a counterflow design and it recovers some heat but it's also quite noisy. 

[GraHal]

Miek, is a heat recovery % quoted on your vent axia single room MVHR or have you ever worked it out (in and out temp diff etc?)?

 

Or if none of above, can you feel the temp difference between in and out with your hand?    

[Miek]

4 hours ago, GraHal said:

Miek, is a heat recovery % quoted on your vent axia single room MVHR or have you ever worked it out (in and out temp diff etc?)?

 

Or if none of above, can you feel the temp difference between in and out with your hand?    

The Vent Axia Tempra is a single room heat recovery unit. It replaces stale air with fresh air that has been heated by the process of heat exchange. So efficient is this process that up to 74% of the heat from the extracted air is reclaimed.

 

That's the claim under ideal conditions.  I've never measured the temps .  It's a lot better than a plain old extractor, and you can see some condenation dripping externally so it must be recovering some of the latent heat. 

 

https://www.extractorfanworld.co.uk/vent-axia-403835-12v-selv-lo-carbon-tempra-lt-heat-recovery-extractor-fan--timer-long-heat-exchange-3904-p.asp

[DamonHD]

Here's a couple that I am using:

 

https://www.earth.org.uk/MHRV-mechanical-heat-recovery-ventilation.html

 

https://www.earth.org.uk/MHRV-Vent-Axia-Lo-Carbon-Tempra-P-REVIEW.html

 

Yes, I think they do their job.  Yes, I also see condensation dripping outside from the bathroom MHRV.

 

Rgds

 

Damon

[GraHal]

Damon, big Thank You!

The 'HR25H Diary' is such a useful source of information on what it is like living with a single-room MVHR .  I'm so glad you referred me to these.

 

I'm saving the Tempra Blog (and the rest of earth site) for tomorrow with my breakfast!