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We have had approx.13 Ariston water heaters fitted where I work. The plumber has not used the brass fittings that are supplied with the heaters but has used grey push on tap fittings. About 8 of these heaters have already leaked and he has been out but I have discovered that he has replaced them with the same grey fittings two of which have leaked again and he has still used the same fittings. The fittings that are connected to the hot water pipe are splitting. I have contacted Ariston and they have provided a picture of what he should use. The plumber has said he will come back and just replace the one that is connected to the hot water pipe. I have spoken to a local plumber and he said he really needs to replace both sides in case there is a problem with the thermostat as both the hot and cold pipes will heat up and the fittings aren't heat resistant enough to cope with the temperature. I need a second opinion please. I think they grey fittings are HEP 20 or something similar. Can anyone give me any advice please. I would be very grateful. Thanks

I have fitted loads of these and repaired many. They all end up leaking where the pipes connect to the boiler. I got fed up once and done some research into it. The problem is that the connectors and the tank on the boiler are made from black iron (epoxy coated in the boiler) and plumbing connectors have usually brass/copper somewhere on them. Add water and this causes electrolytic corrosion between the two materials. To get around this problem Ariston supply two dielectric pipe fitting (effectively and insulator between the two) to connect the boiler. So far so good, except in the UK unlike many other countries we insist on all metal parts being earthed, that includes the boiler tank and also (unless you have a very modern building) the plumbing system. This effectively renders the dielectric fittings pretty ineffective as the circuit is now completed. In my experience they makes matters worst, after a while the connectors look like the battery terminals on an old car. When fitting the boilers now I leave them off.

That said, apart from this problem these Ariston boilers are a pretty efficient and reliable way of providing hot water for landlords. I have just resigned myself to replace the connectors after a number of years. Either that or fit more expensive water heaters with glass tanks. As for your plumber, well he may or may not know about this problem and it's possible that's the reason he has fitted his own connectors. Hep2 connectors will cope fine with the heat from the boiler so heat should not be an issue. Still, if it was me I would feel obliged to sort out any problems if it was within a year or so of fitting. Hope this helps.

Than you for your help. These heaters were installed approx. 2 years ago and nearly all have leaked at the joint on the hep2 fitting. Also Ariston have said that as he has used the wrong fittings it would probably have voided the warranty.
I really am stuck because these have been installed in a block of retirement flats for older people and they are all very upset about it and it has caused many problems for hem already with them leaking into their airing cupboards and through the ceiling of the flats below. Also the buildings insurance would probably not pay out if they know about it and it hasn't been put right.
Why would all these fittings all split in the same place?

It's hard to say why the fittings are splitting without looking being honest. It is very unusual to see a plastic fitting split. One possibility, if they are the larger capacity water heaters, have they had expansion vessels fitted to them ? That's looks like a steel buoy attached to the pipework. They are fitted to allow the hot water to expand. Even if they are not fitted I wouldn't have expected the fittings to split being honest but you never know. It maybe better to clip it in the bud and pay another plumber to replace the connector fittings on all of them for something more robust. If your plumber fitted isolating valves to them it should take less than half hour per unit and will give you peace of mind. In one block of 5 flats I maintain, they were originally fitted before I started with just easy and quick to fit flexi pipes (not recommended by Ariston but I wouldn't let that bother you at this point) I replaced one after 8 years service, two after 10 years service and the other two are still fine. When all said and done it develops as a result of an Ariston design fault but there seems to be no chance of them holding their hands up to it.