hot water circuit

[David Hansen]

On Thu, 31 Jan 2008 08:27:44 GMT someone who may be Fred wrote this:-

The ideal option is to have a radiator in the bathroom to warm the room. This should be fitted with a TRV.

To dry the towels a towel rail should be fitted. This is best not connected to the heating circuit as it will then not be on in the summer (unless it is fitted with an electric element). It can be fed from either the primary or secondary side of the hot water system. There are advantages in feeding it by gravity from the secondary side.

If the towel rail manages to warm the room up enough, as it is likely to do in spring and autumn, the TRV will prevent the radiator coming on.

[Roger Mills]

The pump doesn't have to *suck* water up from downstairs - it simply has to

*circulate* the water in the system. Some of the water which it circulates flows downstairs and pushes the downstairs water up. The pump can only work when the system is full of water, and all the air bled out in order to provide a continuous water circuit.

Chances are that you had an airlock in the downstairs circuit, preventing circulation.

That would be a good idea - and would also make sure that there's no air in or near the pump.

Sounds like the air-lock has moved, and the air settled out somewhere - probably in a radiator.

Dunno - never used them!

[David Hansen]

On Thu, 31 Jan 2008 09:40:57 -0000 someone who may be "Roger Mills" wrote this:-

To add to this. It may be possible to run a pump at down to about

50% of its minimum manual speed, with a sufficiently good controller which produces a good waveform. Less good controllers tend to shorten pump life. Going any lower is likely to damage the pump.

In theory the speed could be reduced to zero, but this would require a rather more expensive controller and pump than is typical in domestic heating systems as it would involve three phase motors fed by an inverter from the single phase supply.

[Fred]

Thanks. I presume I insert a tee with something in the top; what is the something in the top? Do I use a drain c*ck or do I use a 15mm to

1/2 inch adaptor and screw in a radiator bleed valve, or is there a special fitting just for the job, of which I am currently unaware?

Thanks,

[Andy Hall]

That one only has circuit in and out and vent.

It will address the issue of separating out circulating air, but not the risk of pumping over/sucking down. You would have to make sure that the feed is connected close to it to do that. Given that situation, you might as well get the four connection version and solve the entire (risk of a) problem in one go

[Fred]

Thanks for the explanation. I understand now. Because I picked the wrong time of year to do this, I have had the CH on and without the separator there have been no problems yet, other than the downstairs rads not getting warm quickly which I think is because the system is now unbalanced.

[Roger Mills]

There are special fittings. I can't give you a direct URL, but go to

, search for Air Vent, then take the first option and scroll down to parts 6793 and 9178 - which solder onto the end of a 15mm or

22mm pipe respectively, or 16383 which mounts in a 15mm compression fitting. Or any of the others which might take your fancy!

[Fred]

[snip]

That sounds good as I'm not well practiced at soldering yet. The problem with BES is that the postage is quite high, so I need to find a few more things to order to justify the postage charge.

[Roger Mills]

Or try to find something similar at a local plumbers merchant.