leaking dhw cylinder

[andrew heggie]

My wife noticed a damp patch on the ceiling this morning and initial investigation looks like the base of the insulated, copper, hot water cylinder is to blame.

It's about 5 years old and the only markings I can see are:

60 x 12 IDF MD

In marker pen. Plainly it would be easiest to find a match to avoid changing pipes etc.

IIRC it was a bit of a special because of the narrow storage space we had available.

I'm assuming that an end plate in the base has corroded or a joint failed, is it feasible to make a repair?

In the meanwhile I plan to drain the cylinder and turn off the stop c*ck but leave the primary circuit connected to avoid losing any central heating.

I've carefully avoided plumbing for a long while but now I guess I'll have to take the plunge :-(.

AJH

[David Hansen]

On Sun, 18 Mar 2007 14:12:07 +0000 someone who may be andrew heggie wrote this:-

Find out what has failed. It is more likely to be a weeping joint. If it is then:

1) catch the drips and see if it seals itself in a few weeks. 2) if that doesn't work consider gently tightening the joint. How you do this depends on the type of joint. 3) you are very unlucky if a five year old cylinder is leaking. 4) measure the height and width of the cylinder, taking off the thickness of any insulation. If you do need a new one then there are a number of manufacturers like and some of them will make a special one if necessary.

[andrew heggie]

I've investigated the cold inlet, hot outlet and boiler supply and return and there is no dampness around them, the insulation in the area is also dry. There is a weep from the bottom of the insulation around the base, so I'm fairly confident the leak is at the bottom, I'm assuming the insulation is a good closed cell foam bonded to the cylinder.

Good to see there are some optimists left ;-). I'm more of the persuasion that it there if I didn't have bad luck I'd have no luck at all (wheels of fire I think).

That's my view :-(. I still wonder if the base can be repaired, I have spoken with one person who had the same problem where the cylinder appeared to have fretted the seal at the base. Until I remove the thing I cannot see what the problem is and I'm loathe to remove it without locating a replacement first.

Thanks for the url

AJH

[Andrew Mawson]

heggie

persuasion

(wheels of

Even new ones can leak! When I installed the one in my current house one of the rolled joints between the base and side was weaping. OK it was on the ground floor of a three storey house, so the pressure was quite high, but within the limits for the cylinder as marked on it's side label.

AWEM

[John Stumbles]

Check around the immersion (assuming you have one) boss, too. If there's foam up to the boss it could be leaking there and running down inside the foam to the bottom.

[AJH]

Old tanks out and the sludge in the bottom indicates some sort of galvanic corrosion, iron cold water tank and similar main into the house. The new tank coil is bigger so some major pipework needed, my plumber mate is doing it as I copped out and just fitted a new mixer tap in the kitchen while everything is off.

I'm tempted to run some solder around the base of the old tank, to fill any pin holes, and recruit it as the pre warming tank to go with the solar panels I've had for some time but not fitted because the cost of the extra tank didn't warrant it.

AJH

[David Hansen]

On Sat, 24 Mar 2007 12:57:39 +0000 someone who may be AJH wrote this:-

Provided there is enough height it would have been better to buy a dual coil cylinder and connect the panels to the lower coil.

is one supplier.

[AJH]

There is simply not enough space, so the whole system would have needed re jigging. I did look at the possibility but the it doesn't look possible in a 1.5m high by 30cm space. As it wasn't a planned replacement I just took the decision to replace like with as near like as could be quickly sourced rather than do without hot water.

The irony is that had I invested in the solar tank previously I would have saved on the cost of this repair.

I'm still not sure why the sacrificial anode in the failed tank didn't protect it nor whether it will be too thin in places to risk repairing and re use.

From reading various bits on this newsgroup and with experience from a large solar thermal installation at work, if I were to start from scratch I'd go for a pressurised heat bank containing a (vented)coil for the wood burner and backed up by a small combi. The combi would need to be able to accept or blend the warm water passed to it.

AJH

[David Hansen]

On Sun, 25 Mar 2007 12:12:17 +0100 someone who may be AJH wrote this:-

30cm diameter is somewhat small for a hot water cylinder.

[AJH]

Small house! We originally had a larger diameter but the insulation was inadequate.

In fact the potterton suprima and it's predecessor plus this cylinder were able to keep up with the demands of a family of four for 17 years and been more than adequate for 2 of us for the last 17.

Our low DHW costs militate against going overboard for the solar contribution, despite have most of the bits.

AJH

[David Hansen]

On Sun, 25 Mar 2007 13:26:31 +0100 someone who may be AJH wrote this:-

Then I'm surprised that there is room for a second cylinder.

In these unusual circumstances I suggest looking at a solar coil that will replace an immersion heater. There is one at

for 105 pounds plus delivery.

[AJH]

Similar sized under stair space on the ground floor.

Nice idea, I wonder how much power it can transmit.

AJH

[David Hansen]

On Sun, 25 Mar 2007 18:11:44 +0100 someone who may be AJH wrote this:-

Search the forum on the site and if there is not an answer ask.

Obviously this sort of retrofit is not ideal, as it does not heat the whole cylinder and this is why it is not normally recommended. However in this sort of situation it may be appropriate.

The solar panels you have are presumably flat panels. I suspect that the solar coil will be able to cope with all the heat they can supply. It may be worth adopting the low flow approach of

[AJH]

Not that interested to be honest, I see the picture on the site which just suggests it is a 65cms loop of 15mm copper.

That's true of the top fitting but my cylinder has a bottom fitting for an immersion also, trouble is there's only room for ~25cms at the bottom fitting.

I doubt it as I've got about 10m^2 available!

I'm told optimum is about 1 litre/minute per m^2 but I shall experiment, I've got a peristaltic pump here somewhere. I do quite favour the drain back idea.

AJH