Balancing radiators

[John Rumm]

No, the condensing boilers have larger more effective heat exchangers, so even if not running at optimum temperatures will still out perform a normal one. There is a rise in the rate of improvement of efficiency when the return temperature drops below about 54 degrees.

It would be a problem if you wanted other rads to get hot and they were being starved of flow.

Modern boilers will load sense and modulate - so as the differential between flow and return falls (which in a correctly working and balanced system indicates that the house temperature is rising), the boiler will reduce its output to better match the rate of heat loss into the house.

Perhaps, but its not your choice alas. Unless you have the skills to install and commission your own boiler, then you are restricted by what your installer is prepared to use and commission. They in turn are restricted by building regs and Gas Safe etc as to what they can legally install.

You and everyone else. There are not many open flue boilers left out in the wild these days, fortunately.

Yes, but its not an option with any boiler you can buy today. They must exceed 86% efficiency, and big lumps of cast iron with permanent pilot lights don't.

[John Rumm]

If yours does not have a fanned flue, then its probably fairly basic, and unlikely to exceed 70% efficiency. Hence it wastes 30p of every £ you spend on gas.

Compared to yours, a modern boiler is likely to be 25% better.

Much depends on the size of your gas bill. There is often no point in ripping and replacing a working system unless you have very high bills. However when you are forced to replace, you may as well go for the best available at the time.

I will probably rip out and replace my boiler on the grounds of efficiency, but only because a new one will pay for itself in two to three years due to the current size of the bills.

Depends on if you can do it yourself again. A FENSA register installer will only be able to install stuff that complies with modern building regs.

Yup.

More of a Y front person myself, so can't really comment.

[Tim Streater]

You talking about gas or oil, here, John? Or both? Be nice to think an oil job can vary its output. Otherwise, seems to me, there is a good risk it just dumps its heat up the flu if the return temp is too high.

[John Rumm]

Mostly gas. Some modern oil boilers may be able to modulate, but with far less range and flexibility compared to a gas one.

Its probably not that bad - as it can't modulate as much, the flow temp will start to rise and it will then cycle off on its internal stat. Since the pump will still be running, the hot water in the boiler ought not be wasted and can still be circulated out to the rads. Cycling like that is less desirable than a wide modulation range, but it is not the highly inefficient cycling that one associates with old cast iron boilers being cycled on the room stat with no pump overrun.

[John Rumm]

Modern systems are usuually plumbed in a mixture of 22 and 15mm pipe. The upper practical limit on the power transfer of a 15mm pipe is around

6kW, so that alone would not be adequate for a whole system, however is usually ample for a small number of rads.

Balancing is not by any stretch "silly" and is understood by all but the most clueless of installers to make a system work better.

Microbore systems sometimes have manifolds that include individual valves for each outlet. These enable the system to be balanced at the manifold rather than at the rad.

Define "problem". A system without inhibitor will corrode faster than one with it. How fast, and what the consequences of that corrosion will be however are variable.

A clunky old boiler such as yours will care less about dirty primary water than will a modern HE boiler[1]. Even a badly corroded system can seem to be operating well right up until the point the rads start to pinhole, or sludge build up starts to inhibit performance or cause a blockage.

That seems like a rather daft question... there is no fixed level of "cleverness" required of registered professionals, and some are noticeably more clued up than others. Some seem well versed in issues of corrosion, and others would probably think you were talking about dietary supplements, and a baseball competition if you mention electrolytes, and the galvanic series.

If you want a practical example of the effects of inhibitor, see:

Modern boilers have primary heat exchangers with a greater number fins, and narrow water pathways to increase the overall surface area. Needless to say these are more prone to blocking by sludge, and erosion by particulate debris in the primary flow.

[Tim Streater]

Ah. In our case we have only one room stat (and its in the hall). Sounds like I should turn it up high and control matters via the TRVs.

[Roger Chapman]

It is worth remembering that condensing model with oil fired boilers is not so useful as it is with gas fired boilers. The difference between lower and high CV for gas is just over 10% but for kerosene it is only just over 6% and for diesel it is marginally less.

Possibly not. We have had many an argument over the years about where is the best place to mount the room stat and position the radiator without a TRV. Having the room stat in a place where you don't much care how closely the temperature is controlled is not ideal as far as I am concerned. Not only do you have to ensure that the hall warms up more slowly than the rooms where you actually spend your time TRVs are also more susceptible to changes to outside events than a room stat so have to adjusted a bit more frequently if you happen to be sensitive to cold. Be that as it may (and many would dispute the living room as the best place for the room stat) turning the hall stat right up will leave the boiler firing up just to heat the hall to a temperature you really don't want to waste gas on. There is no ideal solution but throttling the hall radiator down rather than turning the hall stat up is the cheaper one for your circumstances.

For what its worth I have separate upstairs and downstairs heating zones with programmable stats in the main bedroom and the living room.

[Tim Streater]

We may move the boiler (get a new one at the same time). I shall attempt to look into better boilers if/when we do. I think out CH piping is prolly a mish mash of uninsulated poorly run plastic and copper. But to fix it means taking the floors up, which is unlikely to happen in the short term. And at the same time I'd try to add insulation under the original 30s suspended floors, and beef up that under some of the floors in the cheap [1] extension to the house. If the boiler project goes ahead I'd also look into RF controlled TRVs.

Meanwhile we're getting a wood-burner put in.

[1] Last summer upstairs floor in new tile-hung extension lifted to add new pipes. I was able to put my hand into the trench in the floor (near one wall) and feel over to the outer sheet on which the tiles are hung - encountering *no* insulation on the way.

[Lieutenant Scott]

I'll try not to sell to an American.

[Dave Plowman (News)]

'They' can't manage it in some parts of Scotland either.

BTW, there is some evidence that hard water is better for your heart than soft.

[thirty-six]

ote:

to mess around like this. =A0If your boiler can't heat all the radiators at= once, your boiler is too small for the system. =A0Even with all my radiato= rs on full blast, the boiler doesn't run continuously.

n't have a correspondingly larger bore pipe from the boiler to feed them? = =A0What twatt designed that?!?

I meant. =A0So, answer the question, do you have a larger diameter pipe fro= m the boiler than to each individual radiator? =A0If not no wonder you need= to do the silly balancing act.

adiators warm up at the same rate and become piping hot very quickly. =A0I'= ve got 22mm from the boiler, through the pump, to two 15mm pipes (one for r= adiators and one for the hot water tank), to 8mm for each radiator (except = the garage which is 10mm for two radiators).

A 22mm pipe can feed two 15mm pipes without loss of capacity and a

15mm can feed two 10mm or four 8mm pipes without loss of capacity. As long as these demands arn't exceeded (with feed lengths within reason) and are all on the same level it wont matter where the rad valves are set

r either, but I've been told by my Aunt in London that it's awful. =A0Can't= they filter that crap out of the water supply?

Hard water is good for your health. Soft acidic water consumed continuously will draw valuable minerals from your body.

you cleverer than a Corgi registered professional?

Huh, for a pressurised system, was that? If the system leaks then it requires topping up with fresh water which introduces oxygen, which if not vented off will cause corrosion. If your autovent is correctly sited, remains fully functional and you top up with a close circuit with a high heat running, the oxygen should vent quickly away out the system, but it's best not to have to put it in, in the first place. Other problems with top-up water could be excessive acidity or excessive mineral content, but this will likely only matter if the leak was great requiring top-ups at least every month.

[Lieutenant Scott]

That's why it's best to steer clear of them :-)

I cannot locate the cameras.

Bloody spellchecker!

Y FRONTS?!?!?! Didn't those go out in the 70s?

Anyway, I said kiss....

[Lieutenant Scott]

around like this. If your boiler can't heat all the radiators at once, your boiler is too small for the system. Even with all my radiators on full blast, the boiler doesn't run continuously.

a correspondingly larger bore pipe from the boiler to feed them? What twatt designed that?!?

So, answer the question, do you have a larger diameter pipe from the boiler than to each individual radiator? If not no wonder you need to do the silly balancing act.

put inhibitor back in. Are you cleverer than a Corgi registered professional?

Radiators are free.

[Lieutenant Scott]

around like this. If your boiler can't heat all the radiators at once, your boiler is too small for the system. Even with all my radiators on full blast, the boiler doesn't run continuously.

correspondingly larger bore pipe from the boiler to feed them? What twatt designed that?!?

So I've nothing to worry about then?

[Lieutenant Scott]

Well cars are generally waterproof and don't blow away.

[Lieutenant Scott]

Well it works just fine.

[Lieutenant Scott]

brilliant system and I have never even serviced it in 11 years!

radiators at once.

from Tokyo.

What? And being an elephant is nothing to do with an elephant being an elephant? Are you high?

[Tim Streater]

What, your arse? Yes, we've noticed (and would rather not have done, if it's all the same to you).

[Lieutenant Scott]

It's a workaround for a poorly thought out system.

So my boiler is actually better! Cool.

Fix it when and if it happens. Anyway the nice clean Scots water will not do that so fast. And when I've removed a radiator (for renovations, nothing to do with the heating), the water in it was perfectly clean.

I know one that didn't understand the word "topological".

[Doctor Drivel]

You really have little clue of why rads are sized up properly and balanced. This is sad.