Most sites recommend a differential across the rad of 12C - but I wonder if this was aimed at higher flow temperatures of yonder times?
I manage with flow of 55C most of the year - so what would be a sensible differential to aim for? 8C?
I've also learnt that different lockshield valves vary massively - I have one set that typically 1/2-3/4 turn is about right. Another set tend to be happy at 1/4 and 3/4 is "practically fully open" as far as temperature diffs go. Quite surprising...
Yup usually. With a modern condenser they often suggest you can go up to nearer 20.
The bigger the differential, the more the condensing efficiency gain at the boiler. However with a flow at 55 its not going to make a massive difference anyway, and you may want it tighter to keep the heat output of the rads up.
Yup, and relative position in the system can have just as much effect as well even with the same valve. Basically you need to suck it and see on each one!
I was looking at it the other way around: if you have a high flow temperature, then you'd expect a larger differential for a given flow rate (l/min) as the temperature difference between radiator and room would be greater, leading to greater loss of heat from the water.
At the other end, if your flow matched the room temperature, your differential would be zero irrespective of flow rate.
That's why I was reasoning, that for a fixed flow[1], that for a low flow temp, you might expect a lower differential?
[1] which is what you're really trying to balance to avoid either pump overload or starvation of another radiator.Or have I short circuited my brain?
And this si why I said I'd like the radiator really hot, hotter the better so more chance of heat coming from the rad to the air, but yuo claimed it;s better toturn the rad down for better cycling.
there has to be one first.
What on earth are you talking about?
another thing you can't work out from basic principles is it.
He doesn't know. That or he has a steam powered bicycle.
So what did I do to piss you off? Or do you do it for fun?
I'm not sure he knows or is in any sort of control of himself.
What has happened is that he has confused you for me (because we both happen to be called 'Tim') and has confused balancing a CH radiator with the overtemp cycling of an oil filled electric radiator (from his other thread).
He is one confused puppy! ;-)
HTH.
Cheers, T i m
There's a discussion about balancing here:
;-)
He works in a student lab that has no heating and has been supplied some oil fill radiators to heat them with (the only type of heating allowed).
His power feed is via some sort of 'snake oil' autotransformer that when under full load, drops to around 200V ;-(
The rads are marked as being 2kW but he measures less, even when on full (of course).
Because the rads are too powerful for their surface area, they 'cycle' on an overtemp stat that doesn't seem to include the smaller of two elements for some reason.
He asks questions like 'how many heaters will I need' but so far has completely failed to even attempt to calculate the heating requirements of the lab(s), in spite of several people pointing him in the right direction re heat loss calculations and building material 'u' values etc.
In an effort to help him improve the heat input to the lab(s) using the heaters he's been given, I've suggested he test them on the higher power element only (lower powered one switched out) as that might mean that the rads won't then cycle, may therefore maintain a higher continuous surface temperature (and therefore heating effect) whilst limiting the maximum load on the already dubious supply and potentially allowing for more heaters to be used simultaneously (so again, more heat into the labs).
Because he has no idea of any 'science', he still doesn't 'get it'. ;-(
Cheers, T i m
The wiki describes balancing, but last time I looked it was missing a rathe r key step. Equal rad temps is a fine point to aim at initially, but what's required in the end is balanced room temps rather than balanced rad temps. The latter does not necessarily produce the former.
NT
Thanks for that link - it's interesting :)
I don't think you are aiming for a fixed flow necessarily... you want whatever flow is required to achieve a reasonable temperature gradient which is something that will vary with rad design and style, what room its in, and where it is in the system wrt to other rads.
I have a large'ish evohome system and thoroughly recommend it. It's great to be able to control the temperature and time schedule of any room from my phone, or the controller, or by twiddling the rad stat. It's also very interesting to use Conrad Connect to plot actual room temperature against the set temperature. Evohome isn't cheap, but it's worth investigating if you're tweaking the heating system.
I think we all deserve an explanation, from basic principles will be fine.
You do know what you're talking about, don't you?
I suspect he has not twigged that there is more than one Tim in this group!
I use Genius
The curves are useful as you say - helps with setting timings of preheat periods.
Don't know anything about Evohome, but the thing I like about Genius is that you can optionally buy wall stats that the user can fiddle with (and which if fiddled with, trigger a manual override for a configurable period of time - eg 1h, 2h).
It's very wife friendly.
For wife friendly, just put up a thermostat that isn't connected ...
This is a wife friendly thermostat: (SFW)
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