EasierVentilation

13 Jul, 2009

Heat pumps and Condensation

Posted by: charles In: Ventilation and Heat Pumps

Almost every day I get called into homes that have heat pumps installed and are still getting large quantities of condensation on all windows throughout the home.
These clients have been told by the heat pump sales person that installing a heatpump, they will remove all condensation. Yes a heat pump (AKA airconditioner) can remove moisture from the room which it has been installed but this can only happen efficently in cooling mode and below 20 deg C, in other words summer.
They have tried running the heat pump for 24 hours over a period of 2 to 3 weeks, they have tried to heat the home to either a higher or lower temperature (both ideas, as advised by various people) but to no avail, they still get condensation. In two cases they have double glazing.
Condensation can only be removed by introducing dry, fresh and wherever possible warmer air through your home by a continuously controlled ventliation system, which complements a correctly sized heatpump. Heating only enables the moisture to be held in or absorbed by the air. When you use a heat pump we tend to heat for longer and this therefore gives us the idea that the house is dryer but then we get more condensation the following morning.  

If you have condensation and want to get rid if it click here.

3 Responses to "Heat pumps and Condensation"

1 | Tim Orum

May 7th, 2011 at 8:35 am

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With a heat pump installed you should only need to introduce a reasonable positive pressure to combat crying windows? assume you probably don’t need fancy controllers just a decent fan ducting and a basic switch or timer?

2 | charles

May 14th, 2011 at 12:10 am

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From previous experience it is the ‘fancy’ controller that makes the difference, as it will bring on the appropriate quantities of air when it is available in the volumes that is needed. If you operate it manually you will have no better than 15 year old basic ventilation systems and a supply of too much cold air when you do not want it. I would not recommend a timer, but i’m curious what times do you think it should be running and what speeds? I’d love to know your thoughts.

3 | Tim Orum

May 14th, 2011 at 8:24 am

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Hi Charles, I would only run it when the condensation on the windows is an issue i.e not when the heat pump is running or during the day I would just try having it come on from the around 10pm - 7am (trial and error) with regard to speed obviously this is fan/house volume dependent and again trial and error . There was an HRV in my house when i first moved in - the only obvious benefit was the dry windows that could have only be caused by the positive pressure as the house had no insulation whatsoever so the temp in the roof space was usually the same as the living area so it must have been the positive pressure the solved the problem - hence my conclusion , why do you think the controller would help?

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