If you're cutting it fine on heat output, are you allowing for the "book" figures for the radiators being quoted for TBSE plumbing, with slightly lower output (5 to 10%) when plumbed BBOE?
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9 years ago
CH design and radiators...
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9 years ago
Doesn't make any difference for a pumped system, and he's not going to be installing a convection circulating system.
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9 years ago
TBSE BBOE?
You mean because of heat drops in the pipes?
Overall I have more than enough - it is just the kitchen and rear lobby are hard to get a lot of power into as walls are very cluttered.
Myson blower in the lobby remains an option though. Will not be allowed one in the kitchen as SWMBO will veto it for being noisy.
She wanted to veto the conservatory one, but I said it was the only practical way to boost the heat there at short notice as it is of course very lossy. The UFH there is more for spring/autumn and to keep the chill off in winter.
Talking of which, I should probably look at antifreeze in the CH circuit as well as inhibitor.
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9 years ago
Oh...
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9 years ago
Sounds like you'd be better off putting in heat pumps.
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9 years ago
Why? That would make it worse with respect to CH flow temps.
Also - I did look at air source heat pumps. The economics are laughable.
They look good initially - with a 100% heat gain over the electrical power input. Until you notice that that is peak rate electricity and gas round our way is 1/3 the price of electricity kW for kW.
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9 years ago
flow at _T_op with return at _B_ottom of _S_ame _E_nd, flow at _B_ottom and return at _B_ottom of _O_pposite _E_nds, also flow at _T_op and return at _B_ottom of _O_pposite _E_nds.
The BSEN 442 spec states that is how rads are plumbed for testing, various sites give different de-rating factors for other plumbing types, but I hadn't picked-up that this was not* relevant to pumped systems.
[*] Can't see how it's /totally/ irrelevant, perhaps it's negligible though.- Vote on answer
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9 years ago
If you search out infra-red pictures of radiators, you will see the hot inlet all rises to the top in the first channel because the convection effect inside the radiator is very strong. It therefore doesn't make any significant difference in the radiator if you pipe the inlet to the top or the bottom - the hot water goes straight to the top anyway, and then uniformly descends the whole rest of the radiator, making for a pretty much perfect contra-flow heat exchanger with the convecting air.
If you run a pipe to the top, you will get a tiny bit extra heat output from that pipe (but not as much as making the radiator wider to take up the space of the pipe).
The only important thing is that the outlet/return must be at the bottom.
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9 years ago
I use one in my main room (which is also my office at one end) when I'm working at home, and don't need to heat the whole house.
Originally bought it for cooling in the summer, but it gets used only for a few days for cooling, but much more for heating.
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9 years ago
Searching for "radiator and FLIR" seems to find better results than "radiator and infrared", but these images seem pretty convincing
Yes, I can see BTSE being a really bad idea!
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9 years ago
You somehow think you can make it drastically cheaper by planning? Just buy a radiator for each room, a load of pipe, and a boiler. Fit it yourself, it's not rocket surgery.
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9 years ago
How do know what size of boiler to buy without some form of planning?
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9 years ago
I agree if it has the purpose of cooling, then it is useful on a single room basis.
My criticism was levelled at whole house systems.
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9 years ago
I'd agree, but IME I'd overspec as much as possible subject to space, appearance, pipe/boiler and common sense.
One reason being it'll get the room up to temperature quicker. The other being that calculations can be defeated by real world use. Opening doors and windows a favourite round these parts ;-)
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9 years ago
Why let it get so far below temperature in the first place?
Did someone fart?
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9 years ago
Every house I've seen has a boiler that can handle about 5 times what it's doing, so I'd buy the cheapest smallest one. The only point in buying a bigger one I can see is that it wouldn't be worked do hard, and would last longer, so that's not about speccing it, that's about how much it costs per size and what money you want to shell out now.
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9 years ago
As much as I'd like to disagree due to me being anal about such stuff, I've found doing all the calculations and factoring outside walls, windows, insulation, ceiling height and everything else to a precise degree has always given me radiators with a capacity vastly greater than required and taking up much more wall space than they ever need to.
With this in mind, when I did the radiators for the downstairs bedrooms/hall I simply got the best sizes to fit in the gap under the window and added some shiny panels to the walls before fitting rads.
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(because they were pretty cheap and potentially afforded a real benefit)
My calculation would have had massive radiators because I'm running a max. flow of 55 degrees however even at such a low temp, with un-insulated floors the aesthetically attractive (to fit the space rather than formula calculated) radiators do the job brilliantly. When the outside temp is higher than 3 degrees causing flow temp. to be even lower than 55 the rad's run to perfection even in the north side bedroom with 2 x outside walls.
So, from personal experience with 3 completely different properties from a 60's semi, a Victorian flat above the shop to a 70's upsidedown detached with half UFH and half radiators I can wholeheartedly say that pedantic calculations serve at best to give you a grossly over-sized radiator that will heat a room admirably with a fraction of the designed flow temp when it's -20 outside.
Having said all that I'd still go through the whole pedantic calculations to satisfy peace of mind, then be happy knowing I can significantly down-size the radiators without worrying about things.
If they do struggle in the coldest of cold winters you can always crank up the boiler to 80 degrees for a week or to to compensate and forget about saving a few pennies from condensing. :)
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9 years ago
Once more I have to agree... If your loft is adequately insulated (and I know ALL about the difference between full insulation and no insulation!) The rooms shouldn't drop more than a few degrees at the very most between morning "off" and evening "on" times. (mine never drop below 19 so I have set-back on each room set to 18.5
You can simply kick the heating to come on earlier if it's not coming up to temp. by a certain time. Same energy input excepting for a bit more electricity to run the CH pump a little longer.
And... in the case of my UFH it's actually far more comfortable to have the floor being "on" all the time by not quite getting to cut-off temp compared to it going "off" (over-heating) and waiting for ambient temp to finish rising before dropping enough for it to kick into life again.
:)
Just more of my casual observations over the years.
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9 years ago
For me is was just a matter of having a combi boiler with big enough balls to feed 2 showers at the same time. This was the biggest load by quite a long way so my boiler normally modulates down to around 50 or
60% total output when doing is regular job of simply chucking warmish water around a load of pipes and radiators.:)
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9 years ago
Because the heating's not on when there's nobody in. It's often 12C inside when I get in from work in this weather.
And the heating's not on because it'd be a waste to heat an empty house.