ch header tank lid

[Mike Penk]

My house is some 30 years old now. From new, the CH header tank had a plastic cover over it with integral insulated panels hanging down all

4 sides. Apparently these can no longer be obtained. Last summer, the overflow pipe discharged and unfortunately dumped a lot of the water inside the insulated panels, ruining the cover (I have since elongated the overflow pipe so that this cannot happen again. I have wrapped the sides of the tank in a purpose built insulated plastic cover but the only insulated cover I could get was a simple flat one of similar material, which requires its own tank cover beneath it to support it (otherwise it would just fall into the water!). I've constructed a cover out of painted (breathable) plywood, with ledges all the way round to prevent it moving sideways, that fits snugly round the top of the oblong tank. I've permanently fixed two elasticated straps to the top of the cover under which the insulated panel can fit. On checking the panel a while ago, I found the under surface of it saturated with what I assume is condensation. I also seem to remember that the original plastic cover ended up like this as well. I've tried to alleviate the problem by raising the cover about 12 cm all round to allow the ventilated loft air to circulate under it to some extent, but this has made no difference. I'm obviously concerned that if left in that state for any length of time, the plywood cover will eventually be adversely affected, despite being painted.

I plan to re-paint the lid in deck paint for added resistance to the condensation and have also considered making one out of 1" polystyrene, but strength may be a problem. Does anyone have any answer to this problem. Can insulated plastic covers similar to my original still be obtained? Also, will the under surface of the cover always be saturated in condensation - presumably particularly in the colder months?

[Andy Hall]

There is a much simpler solution.

These tanks, covers and jackets are very cheap - you can buy all three for a fiver, or separately.

Look at

stock codes 11445, 11446,11447

Your local plumber's merchant should have them for the same or little more.

With a vented CH system, the water often becomes warm, depending on how far the feed pipe from the bottom runs before it reaches the primary circuit pipe. Expansion of the water takes place up this pipe, so dependent on volumes there may be some warming of the water. THis will lead to water vapour which will tend to condense on the underside of the lid put should drip back in - and is normal.

What you should check for though, is that the system is not pumping over. This is where water is flowing out of the vent pipe and into the tank. In that case the water will become hot, of course, and this is not desirable because you will introduce dissolved air into the system and promote corrosion.

The reason for this, if it happens is too great a pressure differential between the feed and vent pipes and is either because they are connected incorrectly to the circuit (should be at points no greater than 150mm apart) and/or because the pump setting is too high.

.andy

To email, substitute .nospam with .gl

[IMM]

This can be avoided by inserting a larger bore feed pipe, then any expansion is inside the large bore pipe rarther than into the plastic F&E tank.

[John Stumbles]

news:brv9fi$cap$ [e-mail]...

Sort of. The water will still expand into the f&e tank and the level will rise. Depending on the capacity of water in the feed pipework between the tank and wherever lower in the system the water is hot, warmed water may not rise to the tank. You could run your feed pipework in 100mm to ensure this :-)

However if your tank is well insulated and fitted with a lid which is not affected by condensation (and does not allow it to run off over the edges of the tank) then the warming of the water in the tank should not be a problem.

-- John Stumbles

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-+ I read a book on improving your memory but I've forgotten what it was called

[Andy Hall]

No need. He does a good job himself ;-)

.andy

To email, substitute .nospam with .gl

[Mike Penk]

Hello Andy and thanks for the reply.

I have contacted the web site you mentioned and am awaiting a reply. The header tank they offer is very nearly but not quite the same dimensions as mine. I therefore doubt that the lid they offer will fit.

Without the lid, unless the insulation product they mention forms a cover as well as insulating the sides of the tank, I'll be back to square one and will have to persevere with the lid I've made.

It has occurred to me to see whether the makers of my tank are still in business. They may be able to help.

Regards

[IMM]

Or just a section of 28mm. It can be calculated by noting the water level in the F&E tank when cold and then hot and size the pipe to suit.

Warming water in an F&E tank is wasted heat. It acts a heat sink in very loft. Best have a one pipe combined F&E and have this as large as possible. The minimum size these is 22mm.

[IMM]

F&E tanks with lid and insulation jacket are very cheap.

[Mike Penk]

I've now had a reply from the web site you mentioned and unfortunately the lid of the tank they offer is just too small to fit my tank. Also, the insulation kit they offer is simply a wrap-around for the sides of the tank, which I aleady have, and a simple flat top which requires the tank to have a lid.

I'm not even contemplating replacing my tank, so I shall have to persevere with the lid I've fabricated, painted with deck paint. Thanks for your attempted help, anyway.