hi all - just another follow up question on this. I am minded to go back to octopus. Quick question - their design temp is 21 in living areas and 18c bedrooms. 18C sounds quite cold to me! Is that normal, or again could that be an inidication of undersizing?

Posted by: @pie_eater

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18c bedrooms. 18C sounds quite cold to me!

All depends how you like to sleep, 18 and below is my preference. We never take the summer quilt off and have deliberately put way less UFH pipes in the floor, so it can't get get warm in the bedrooms.

21C in the bedroom would be very warm , my wife would disown me! 18C is about average although many like it cooler! The sleep foundation say:

The best room temperature for sleep is approximately 65 degrees Fahrenheit (18.3 degrees Celsius). This may vary by a few degrees from person to person, but most doctors recommend keeping the thermostat set between 65 to 68 degrees Fahrenheit (15.6 to 20 degrees Celsius) for the most comfortable sleep.

@pie_eater I'm arguing with 🐙 on this too. It's very outdated thinking from CIBSE about 'how' we live in our homes.

Many of us now work from home and for me that has been in my bedroom but I have 2 bedrooms and I want number 2 to double up as a studio (I'm a journalist and I make radio programmes sometimes). 

Thus I want them designed for 20º and if necessary they can be cooled by setting back the temps at night. Or better still by opening a window and falling asleep listening to the owls that live nearby. 

I have a square room in the centre of my home called a 'hall'. CIBSE (and thus MCS) think it's a passage from the front door that has no other function and can be designed at 18º.

Not in my house... it's a place to do yoga or work out, it's a playroom, it's somewhere quiet to read AND via the front door it provides constant access to my terrace and garage side door where I have a freezer, tumble dryer, workshop, recycling (even a phone line although I didn't put it in). 18º will leech heat from the rest of the house. 

MCS (the guidelines/rules) and CIBSE (the architectural body) need to move forward into the 21st century and focus more on *how* people live. It's really annoying. 

@pie_eater OE, like other installers adhere (too closely I feel) to the MCS and others guidelines - which as others have pointed out, are outdated. 18 degrees C may not be far from most people’s idea of comfort in a bedroom but, adhering to 21 degrees (no matter what!) in living spaces and bathrooms is I feel impractical. I have posted before on this subject and you may need to remind installers that guidelines are just that and not mandatory! I required 25 - 26 degrees for the bathroom and that is what I requested from my installers who made appropriate allowance on emitter size to achieve. I had previously had the conversation with OE on this very subject and had to remind them that guidelines are just that and that customers are permitted to request variations to these tables. OE could not oblige due to my requirements being ‘out of scope’ as they put it so I never completed the discussion on the required bathroom temperature. Regards, Toodles.

Its a fair point that rooms these days can be multifunctional although in terms of heat pump output and heat loss, it would only be an issue on a couple of (coldest) days every year.

Ive taken the view that the only room I need really warm in my house is the lounge at night. It is therefore the most insulated in the house and has two radiators. This enables a lower flow temperature to be set which is also adequate for the other rooms.

@bontwoody On top of all this comes the individual’s (or family’s) needs which vary to some degree (!Sorry!); I have seen mention of RHH subscribers preferences ranging from ~18-19 degrees C to my own of ~22.5 degrees C and even a little higher than this. Though the likes of MCS are quite rightly aiming for efficiency and might well wish to help reduce energy consumption, surely user’s comfort and special needs need to be considered in the equation. Regards, Toodles.

@toodles absolutely, I, like you prefer 22.5C so my house is configured to achieve that where I need it. Its worth pointing out I suppose that if you wanted a bedroom warmer than 18C after the install (if they wont do it) it just to increase the radiator size in that room.

@bontwoody I feel that changing the radiator post-install is a retrograde step and such provision should be carried out in the first instance; why should we (the purchaser and owner of the dwelling) be paying for a system that would not provide the level of comfort we have requested initially? Sounds like the tail is wagging the dog to me! Regards, Toodles.

@toodles Well to me, it would depend on the deal I was getting, If the quote was substantially cheaper than others and it was take it or leave it, then I wouldn't mind a bit of retrofit to save money, but I appreciate everyone is different.

Posted by: @bontwoody

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@toodles absolutely, I, like you prefer 22.5C so my house is configured to achieve that where I need it. Its worth pointing out I suppose that if you wanted a bedroom warmer than 18C after the install (if they wont do it) it just to increase the radiator size in that room.

It could even be that the present radiator size is adequate, and that the flow rate has been reduced with the lockshield valve to lower the temperature to 18C. It should also be noted that the actual heat loss of bedrooms can be lower than the calculated value, due to heat rising and solar gain through the roof.

@derek-m Good point!