Viessmann boiler failure

[AlanBeckett]

I don't mind the Ribbed Copper ones.

Alan

[ed731pdh]

Even they can fail in service, they are very thin walled compared to copper tube.

[pwdrive]

I've used both types, still got braided flexi's feeding the bath taps and also the toilet cistern, our hot water doesn't get much above 60 degrees C, the boiler is wood powered.

Lawrence.

[ed731pdh]

I moved away from flexi's a long time ago. When I plumb in stuff I make sure it's done using 15 or 22mm copper tube, and yorkies. Ok, time consuming and a bit ball breaking making up the geometry but it's fire and forget with no high risk of failures. In addition, unlike flexi's, you always get the full delivery rate up to the tap, which if you have a gravity fed system from a loft tank can make all the difference.

[pwdrive]

Yes delivery rate, tell me about it, our hot water delivery rate is very low, it's due to the height of the house, single storey and not very high, all a bit of a squash so far as everything goes.

The bottom of the cold water cistern is only just above 7' from the floor level, the height of the top of the hot water cylinder is only about 2' below the bottom of the cold water cistern, I can't increase that distance because of the height above hearth level of the wood boilers primary flow pipe.

Lawrence.

[ppppenguin]

Not too hard to pump the entire HW system. I have conventional gravity HW and pumped showers. These are excellent. I have enough head for decent flow at the hot taps. A lot of modern mixers are rather small bore and not suitable for a low head.

[Refugee]

I changed a loo a few months ago because it was one of them 1970s ones that always left one bit behind each time you flushed it. The bodge was to "crank" the handle to boost the flow. The return spring on the handle shattered and mangled the the lift membrane so that it had to be flushed with a bucket of water for a few days. It was not too bad to get a new one in as the stink pipe was adjustable and the height of the inlet pipe was close enough for me to hook up again. There is a little bit less elbow room on the non loo roll side. The pesky screwdriver operated stop valve was rusted solid as is the inside stop cock so it was time to put my arm down a hole in the pavement to shut it off. Pipes are such a pain when they need to be fixed.

[ed731pdh]

One of the biggest c/h bodges we found in this house was on the upstairs radiators which had sadly been put in in such a way as to intercept every joist. Wickes sell an expanding connector which uses an internal o ring to seal the sliding section. Absolute bodge, they leak from brand new, and ones in service have to be left alone which means decorating behind the radiator is a no no.

What I did for one was measure the distance the unit had to stretch. remove the outer chrome coat, remove the inner o ring, and then braise the whole thing into one solid lump. That sorted it, no more leaks.

[Radio Fixer]

For those who are thrilled about still having 20 - 25 year old cast iron boilers I would say don't leave them on if you go away for long, like over night !!

We had one and the boiler was still good but the gas valve will be the same age and that is a disaster of a weak link. Fortunately we were at home and during the night woke up to find the house sweltering hot and the sound of boiling water. The CH time clock had turned off but the gas valve had remained open ....

I asked the engineer who replaced the boiler and of course the gas valve with it what eventually happens. "Bottom melts out of the header tank and then you have hot and then cold water running through the loft ceiling. Yes! it happens ...".

New boiler with many more built in safety measures, like two gas valves in series has been in use for some years now with no problems. I feel confident about leaving it on whilst we are away and it must have paid for itself in economy over years we have had it.

Gary

[Mark Hennessy]

There was a tragic case a few years back where a faulty electric immersion heater stuck on. Eventually the water in the plastic header tank in the loft became heated, the tank failed, and scolding hot water came cascading through the ceiling.

When searching for a link, I came across many similar cases of death and serious injury. This is the one I had in mind: http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

New immersion heaters have 2 thermostats in series.