Green Building Bible, Fourth Edition |
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These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment. PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book. |
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Posted By: djhApparently some boilers need some radiators connected at all times in order to dissipate excess heat. So I'd read the boiler's manual. But I'm no boiler expert.
Posted By: TimSmallThat should be fine. Make sure you don't drain the primary water (the water that goes around the radiators) from the boiler, or the DHW will stop working too.
Combis do:
In CH mode: Gas heat -> primary water -> radiators
In DHW mode: Gas heat -> primary water -> flat-plate heat exchanger -> DHW water to taps
The primary water and pump which circulates the primary water (either through the rads or the flat plate heat exchanger) is the same water (which is why they can do CH or DHW, but not both at the same time).
If you are keeping the boiler in the long run, but changing the CH emitters (rads and/or UFH), then make the CH system low temperature (e.g. 30°C to 40°C max temp) - then your boiler will run a chunk more efficiently, and you can change over to a heat pump in the future without making other changes to the CH system.
Posted By: kristevaThanks Tim, so with a combi you can't take a shower and have the CH on?
Do I make the CH system low temp by oversizing the rads? I was actually looking at the vague possibility of an air to air heating system on the ground floor which will be open plan and keeping the rads upstairs.
Posted By: WillInAberdeenheat pumps are available now that work at condensing boiler temperatures, so low temperatures are not as vitally important anymoreThat's good, and does change the game - but how tolerant is these newbies' COP, of larger delta-t between source and heating flow temp? Is it just not so bad as previous; or is it just as good, so we can forget about trying to achieve low delta-t?
Posted By: SteveZMy boiler has a switch which allows you to select CH or DHW or both. I guess not all boilers do?
Posted By: CX23882I'm a big fan of increasing the size of radiators whenever they need to be replacedMe too, if UFCH isn't an option. For interest, since 2017 it's been mandatory to install low-temperature radiators in France if both radiators and boiler are replaced.
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