The story goes that you are interested in a heat pump so you start getting some quotes and talking to some folks and then…the heat loss survey figures between companies are different from each other, the heat pump size recommendations are different…what is happening?
Watch this video to better understand the 6 reasons we’ve seen for the different heat loss figures.
The long and short of it that heat loss surveys can vary wildly depending on these main factors:
No.1 The experience of your surveyor: the more detail orientated they are, the better. If they miss details like a solid floor vs a suspended floor or double gazed vs single glazed etc…your results will vary.
No. 2 Software compliance: is the software they are using applying the current standards BS EN 12831:1-1:2017 rather than the older 2003 model? This one thing can have a HUGE impact on the the heat pump size being recommended. (You’d be surprised how many are using outdated models which cost YOU more money)
No. 3 Room temperatures effect the heat loss (and emitter outputs) of a property. Make sure you compare apples to apples: one company may use older CIBSE room temperatures with differing temperatures for different room types (18c bathroom and 21c in living areas) and another may use blanket temperatures throughout the house. Both can be correct in differing circumstances but this comes bac number 1 again…surveyor experience!
No. 4 Design Outside Temperature: are they using the 99% or 99.6% column from CIBSE to design to? The majority of companies use the 99% as it is a warmer temperature to design to and will result in smaller radiators and heat pump sizes.
This can be a mistake as the house may then struggle to heat sufficiently when the temperature drops below this warmer temperature.
Southeast England areas like Surrey Hills have a 99% temperature of -1.7c and the 99.6% column is actually -3c for most properties (unless the altitude calls for design alterations). We choose to design for the worst case not the best hopeful case.
No. 5 Software capabilities: If the software they use does not have the CAD abilities to accurately map both the 2d and 3d (floor plans and elevation plans) then you simply cannot calculate an accurate volume and thus heat loss for a room.
It is stunning how many apps cannot do this fully. Heat Punk is by far the most precise and simplest to use for accurate mapping when designing a low temperature Air Source Heat Pump System.
No. 6 Fabric: if your surveyor does not know how to identify cavity walls, header and stretcher wall, retrofit insulation etc. then they will show up as very different heat loss results….the more information you can share with them, the better your results.
BONUS at the end of the video: why does so many heat loss reports say 10kw heat loss and then have a 12kw or 14kw heat pump recommended….isn’t that bad?
We install Viessmann Air Source Heat Pumps (we thinkthey are the best for longevity, quality AND user experience AFTER the installation) in the Surrey Hills and East Hampshire.
Air Source Heat Pump Installations begin at £12,000 post BUS grant and we offer:
A full refund on your survey fee (£300+vat) if you sign and clear the deposit within seven days of receiving your proposal
AND
Offer a 50% discount voucher on future heat loss surveys on residential properties for you or your friends and family for your 5 star Google review (£150+vat value)
AND
Give you your first year heat pump service FOR FREE if you do both the above (£250+vat value)
P.S. We also pay you £300 for any referral introduction you make to us that goes on to have an Air Source Heat Pump installed with us
That’s over £1100 value, back to you, for allowing us to give you the best low temperature air source heat pump system available.
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You could just a book a survey today using the contact form below…because why would you let your family be warmed by anything other than a Viessmann Air Source Heat Pump in your Surrey Hills Homestead?