Dimplex cylinder

[Whn1]

Hello my favourite people!

Ok dimplex pressurised cylind (similar to megaflow)
the cylinder is direct, in a newish build flat.
130ltr has two immersions, when you switch both both immersions on the water gets hot as it should but the cylinder loses heat very quickly, like if you have a shower the water will be cold again in 4minutes ( no chance of a bath), also if you leave the immersions on continuously it doesn't stay hot.
The homeowner has had the plumber out and the electrician who both claimed to have fixed it but quite clearly didn't know what they were doing or how the system works, the rads are electric and run off a programmer.

Phone this kinda makes sense, thanks guys.

Tony

 

[shaky]

May be faulty immersions mate I had one the other day were the element was touching the stat pocket so it was getting the water hot but not a full tank as it was cutting out to quick ether bend the element out a bit or change it. I changed it and all was good.

 

[Whn1]

But both elements? Also is there a difference between the top and bottom immersion?

Excuse the silly Q's I don't usually deal with these elec systems.. Not a fan

 

[shaky]

No difference mate you will not be able to have both on at the same time the bottom one will come on at night usually around 1am till 8am and the top one as a boost it may be on one the stats faulty and the other elements touching check the cut out on both stat and make sure nothing has tripped if not drain the cylinder get them out and have a look. Hope this helps mate.

 

[Howsie]

No reason why elements can't run at the same time. Depends on how it's been wired/set up.

Silly question but is it plumbed right?

 

[Whn1]

No reason why elements can't run at the same time. Depends on how it's been wired/set up.

Silly question but is it plumbed right?

Yea plumbing is sound, not much to it as its direct, both immersions are just wired to spurs.

 

[markfxy]

the bottom one will be economy 7 it sounds like this ones not working if its just relying on the top immersion then the volume of hot water will be reduced and could easily be used up with one shower

 

[tamz]

Cylinders with 2 immersions are usually wired with one (the bottom one) to off peak. It is unusual to have both wired to standard tarriff.
The bottom element comes on at off peak times (times depend on what plan) and heat the full tank. The top element is meant for a back up during the day if you run out and gives under half a tank (or there about) of water. Sounds like only the top half is being het.
Easily checked with a multimeter or even a neon screwdriver. Take the cover off the elements and test them.

 

[Whn1]

Ok tam is this easy enough to check? Do I just check the immersion has 240v to the live or is there a switch I can check after the stat?

Excuse the wording, never had to check one before..

 

[jtsplumbing]

Tip if your going to replace bottom heater use a 14" one instead of the 11" are you in a hard water area ??.

 

[Whn1]

Tip if your going to replace bottom heater use a 14" one instead of the 11" are you in a hard water area ??.

Na the areas pretty good, tbh it's my girlfriends flat and I've been promising to look at it for a while and I wasn't completely sure about the boost, economy 7 stuff.
Shame There isn't gas here because I would rip this pants out!

 

[tamz]

A multimeter or test lamp is best but if you only have a neon screw driver test for live on both sides of the stat.
If the bottom element is on off peak there will be a big ugly immersion time switch type thing in the kitchen or in a cupboard.

 

[Whn1]

No there's nothing like that, an rcd and a couple of wiring centres.

 

[tamz]

Test it to see what it is doing.
You could tell her to knock on the house next door and ask how theirs works :lol:

 

[Whn1]

I feel a bit embarrassed that I haven't sorted it yet, you know how it is, my bathroom at home is falling apart....

 

[tamz]

Don't let it worry you. Its all part of the deal :smile:

 

[SafeGasInstall]

sure there no leaks on the hot water pipe work some where and cylinder refilling it self and therefore cooling it self ???

 

[Whn1]

Na I checked the safety devices etc and there's nowhere else for a leak. I think rams hit it spot on, when she got the sparks and plumber out (wish I was there) because she was unsure how to use it or if it was working properly she said they swapped the immersions over, I'm guessing one was faulty so they put the working one in the boost.. So she'll get a quicker hw response... Pulled a fast one what'd you think?


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[Nostrum]

Only thing I can think of if the immersions are OK (which will need testing first) is de-stratification caused by either a poor design or possibly excessive inlet water pressure?

 

[Howsie]

Only thing I can think of if the immersions are OK (which will need testing first) is de-stratification caused by either a poor design or possibly excessive inlet water pressure?

Which is where I was coming from with the plumbing questions. I've seen these plumbed in upside down before, the cold was coming in the top...

 

[shaky]

It's not passing out the prv or t&p valve is it? Check the tundish

 

[Whn1]

I've checked the safety devices and it's plumbed ok, theres nothing to the system and the pipes are easily traceable. Haven't checked yet but it has to be the bottem immersion.


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[Howsie]

Well hurry up then!

 

[zzzjim]

If your not a great electrician , watching how quick electric meter spins/pulses , with Immersion , or a kettle on , then off . To get a feel of when / how long it uses plenty of electricity for (ie heating up )

Good for clues without messing with any wires !
and minimal test gear

 

[zzzjim]

Another question , you said Rads were electric .

Do you mean like electric storage heaters , or are they using the Hot water !

(Electric boiler -never seen one)

 

[Resolute]

I'm guessing from the sound of the set up that it is an economy 7 tariff. The newer meters don't require a time switch so not that easy to tell.

Have you tried replacing the thermostat in the bottom immersion?

 

[Whn1]

If your not a great electrician , watching how quick electric meter spins/pulses , with Immersion , or a kettle on , then off . To get a feel of when / how long it uses plenty of electricity for (ie heating up )

Good for clues without messing with any wires !
and minimal test gear

Im ok with wires, just never looked too far into these before, I'll sort it....... Soon haha,
Thanks for the wonderful advice people!
And no resolute, I haven't even taken the cover off yet, I'm working sat and Sunday too so I'll get stuck in when I get some free time..

 

[Resolute]

Good luck with it! You know where to come for help if you get stuck!

 

[zzzjim]

Im ok with wires,.

Happy twiddling ( No insult intended )

 

[Whn1]

Ok boys finally took the cover off of both immersions, checked the top one and it had 230v going to it, checked the bottom and nothing.... Undone the spur and the supply and load were dead, nothing going to them, checked the rcd for any trips... All good. Is this just a matter of what tarrif she's on?