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Abbo · Joined: 02 Oct 2006 Posts: 25 Location: South Staffs

Hi,

Some months ago I changed a hot water cylinder (combination type) c/w new thermostat (14" incalloy with resettable thermostat). My friend called me to say that the immersion had stopped working but the electrics hadn't tripped (unlike the last time it failed) I said about the resettable thermostat and was told that the button had 'popped' out. She pressed it back in (and it stayed in without popping back out) and appeared to be heating up again. Although I'm Part P qualified (allied trades), I'm more familiar with plumbing. If there was a major problem with the thermostat, surely the resettlable button would not have allowed it to reset? (Why have a resettlable thermostat if it was only masking a problem? Surely it would be a fail-safe and not allow any resetting if there was a major problem?)

However, I would like to bow to any of you electrician's superior knowledge, to ask as to whether, the thermostat tripping is the sign of a possible future problems or whether it is just a possible surge that could have caused it to trip in the first place? Are there any tests on the thermostat that I can do to check it, or is it a case of changing it for a new one to be on the safe side?? Wink

vince knight · Posted: Wed Jan 30, 2008 4:02 pm Post subject:

The trip is only a thermal device and is governed by the temperature of the tank.
My advice would be to turn the stat down a touch (max 60).

Vince

Abbo · Joined: 02 Oct 2006 Posts: 25 Location: South Staffs

Cheers Chap.

My friend called again this afternoon to say it's tripped again!! So I'll see if turning the temp down and resetting it works. If not, would you suggest changing the thermostat? Rolling Eyes

Hopefully, like you say turning the temp down should do it.

vince knight · Posted: Thu Jan 31, 2008 8:16 pm Post subject:

we have had some over sesitive thermal trips in the past but not for a while, but it is possible.

Vince

Abbo · Joined: 02 Oct 2006 Posts: 25 Location: South Staffs

Hi Vince,

Just thought I'd let you know, that as the thermostat still refuses to play by the book I thought I'd put a new one in, so I went to my local CEF and guess what; they tried to sell me an old type without the safety cutout!! I questioned as to whether they should still be selling that type and he just shrugged his shoulders and said he hadn't heard anything, but I pointed out that it came in in 2004. Still got the blank look and shrug of shoulders so I left it!!

I not sure if it was a case of ignorance or if he thought he might be able to get rid of his old obsolete stock (It looked rather old and dusty for starters!!) and of course me be a girlie and I was in civvies???? But I still find that worrying if he did think I was just some customer off the street???

But being self employed plumber I didn't want to risk it, especially in the light of the recent publicity with that stat overheating in Devon. I know that was slightly different in the respect that it was the cold tank that was incorrectly installed etc, but either way, am I right in assuming that he shouldn't have tried to flog it to me? I know some electricians prefer the old type, but I'm not willing to risk my Part P etc!!

Cheers

Wink

vince knight · Posted: Tue Feb 05, 2008 9:48 pm Post subject:

He was VERY WRONG in trying to sell it to you!!!
ONLY fitt a stat with thermal cut-out, Plumb centre or similar would be a better bet.
The tank in devon failed because the hot water tank over heated and boiled over up the expansion pipe and into the cold water storage tank, thus heating the storage tank and causing it to fail.

You did good
Laughing

vince

Abbo · Joined: 02 Oct 2006 Posts: 25 Location: South Staffs

Cheers chap,

Yeah I was quite gob smacked when he gave the stat to me! When I said I wanted one with a thermal cut out he actually gave me the address of another electrical store (It was literally across the road on the Trading est!) The old lad behind the counter was quite surprised they'd tried selling an old stat.

Guess where I'll be taking my custom in the future!!

I did try City Plumbing and PlumbCenter before but they didn't have any in stock at the time!

Just thought I'd let you know that one! Especially with stuff like that in the news I was well stunned! Shocked

Well at least I can sleep well at night! Wink

Thanks for your help again.

Very Happy