Unvented immersion elements

[pertinky]

I spoke to the installer whos predictably busy.

He agrees theres no thermal cut off. I'm a bit concerned that if this was regulation does my installation breach it given its only a year old?

He said I should be able to replace the thermostat myself. I'm fairly comfortable with simple electics.

I presume I still need to check the continuity before going out and buying a replacement stat?

Hopefully theres some sort of model number on it for reference...

 

[Madrab]

I would always do a continuity test and a circuit test back to the supply just to rule out anything else before replacing.
I wouldn't take the part no, you want one that takes an OH stat. Do you have the MI's, they would suggest a suitable immersion heater that suits their setup I would think.
All that being said, I am not sure where the G3 regs stop when it comes to working with un-vented systems and whether it requires a suitably certified engineer to do the work and sign it off.

 

[pertinky]

I would always do a continuity test and a circuit test back to the supply just to rule out anything else before replacing. Don't forget to get one that takes an OH stat

I thought the thermostate/OH stat is the same thing?

 

[Madrab]

Apologies, blonde moment. You're quite correct.

I was in the 'replacing the element' train of thought and getting a OH stat that has a reset, much more convenient, saves having to replace if it trips.

 

[pertinky]

Apologies, blonde moment. You're quite correct.

I was in the 'replacing the element' train of thought.

If you are replacing just the OH thermostat then you want one that has a reset, much more convenient, saves having to replace if it trips.

Hehe, thanks buddy! I'll test on the weekend and see how it goes.

 

[hazetimesfive]

the installer should have fitted the genuine part, SH001.

get him back and get him to fit the right one.

 

[Agile]

I don't understand how this has come about but there must be a separate o/h stat on all unventeds.

Either in the immersion heater unit or separately on the cylinder.

You are assuming that the stat has failed but as far as I can see no test has been done to see if its the stat or the element.

Replacing the stat ( using one with built in o/h device ) is a very simple job. Quite within the capabilities of a DIYer although my interpretation of the regulations is that a G3 qualified person should be doing it.

Replacing the element is a much more involved job and draining can often be difficult too.

Tony

 

[hazetimesfive]

If the engineer had done his job correctly then this wouldn't be an issue

 

[Agile]

It all seems very odd!

A new cylinder only a year old apparently not fitted with the correct safety parts!

An installer who seems oblivious to the safety requirements! And perhaps installing them when not qualified!

Tony

 

[matt1e]

yes it does sound like the o/heat stats have tripped and can be reset, but you have received the correct advice if they have both tripped then get both thermostats changed at the same time it will work out cheaper in the end

Just a quick pointer on this Ian, a bottom stat that has failed closed will operate the upper elements cutout regardless of whether it is getting used or not due to it being immersed in the same body of (overheated) water
there is no need to change both, but due to the low price of them,agreed it does make good sense

Matt

 

[pertinky]

If the engineer had done his job correctly then this wouldn't be an issue

You'd have thunk that!

But the installation has been registered. If its not been done right then he wont have a leg to stand on legally speaking!

He was pretty sound so I'd rather give him the benefit of the doubt. I'm still fairly naive about the unvented system so maybe I'm missing something! I ordered the cylinder, so I'm responsible if it didnt turn up with the right parts!

I'm planning on doing a continuity test Saturday when I can turn the electric off and its light (I know I can probably just flip the switch on the spur, but being a novice I'm more comfortable doing it this way for now).

I've had another look at the element and I definitely can't see any red button. The only movable part under the cover is the thermostat (the light blue component).

The horsmann timer wont have a cut off in it I dont think and the two spurs are 1) both elements 2) the timer itself.

 

[pertinky]

yes it does sound like the o/heat stats have tripped and can be reset, but you have received the correct advice if they have both tripped then get both thermostats changed at the same time it will work out cheaper in the end

Just a quick pointer on this Ian, a bottom stat that has failed closed will operate the upper elements cutout regardless of whether it is getting used or not due to it being immersed in the same body of (overheated) water
there is no need to change both, but due to the low price of them,agreed it does make good sense

Matt

The top element is working fine! So maybe its not the stat afterall as you quite rightly put if it was too hot BOTH stats would trigger.

 

[Agile]

You can test it by just measuring the voltage inside the immersion unit.

Tony

 

[pertinky]

Hey guys,

Got around to getting a multimeter and testing it.

The resistance across the element was about 180 ohms (0.018 on 2k)

The resistance across the thermostat terminals was 20 ohms (0.2 on 200)

I think im reading it right, but it still doesnt help me figure out why its not working!!!

Is it worth changing the thermostat first and see if it works before i call out the installer?

 

[EFLImpudence]

The resistance across the element was about 180 ohms (0.018 on 2k)

That's 18Ω which would be correct(ish) for 3kW element.

The resistance across the thermostat terminals was 20 ohms (0.2 on 200)

That's 0.2Ω which doesn't mean much except that they are connected.

I think im reading it right,

Nope.

but it still doesnt help me figure out why its not working!!!

It doesn't but the element would appear to be alright.

Is it worth changing the thermostat first and see if it works before i call out the installer?

No.