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Posted By Topic: Hot water cylinder not warming

Mar 26 2020 13:06

Hey guys, I don’t have much experience with hot water cylinders but what could stop the hot water cylinder warming from the electrical side? The cylinder is cold during the day and warms up over night, plumber has been out and said it’s all fine from his side and saying it’s electrical

Mar 26 2020 13:09

Forgot to add it’s a brand new cylinder installed

Mar 26 2020 13:36

Hmmmm. If it's a brand new cylinder put your hand on the hot pipe coming out of the cylinder. Typically these have red rings around them or are at the top of the cylinder. If the pipe is hot then it will be the tempering valve which mixes cold water to the hot so it coomes out of the tap at 55deg.
If it is cold then there could be a number of things.
Using too much hot water. If it is a new high pressure cylinder you will have a lot more water running through the shower than you're used to if you have changed from a low pressure. Use an actual timer & see how long your showers are - I timed a customer in the shower for 45minutes & he complained later about running out of hot water on a huge cylinder.
You could be on night rate only where it doesn't heat during the day.
If the water is just luke warm it will probably be the element. The element can blow if it is turned on before the cylinder is full - usually due to a miscommunication. WHen the element blows half the current goes through the element & the rest runs through the water so you only get half the heating.
Let us know how you get on

Mar 26 2020 19:00

Could also be a leak, no usage at night means that it gets a chance to pump some heat in

Mar 26 2020 20:27

Hmm even during the day when the shower isn’t being used it will drop down to being stone cold and then heat up over night again for the morning, plumber is saying it’s something electrical but the breaker isn’t tripping or anything to not be supplying power

Mar 26 2020 21:05

a full hw cylinder should last for a couple of days hot with no usage and no leaks, if you're not using it there's a leak. if it's new it's under warranty, talk to the electrician who did the job, their name will be on the certification for the electrical side of the job, he will be able to help. if the plumber wired it string him high

Mar 26 2020 21:37

Is it a new cylinder replacing an old? No problems before? Gone from an 80 gallon to a 40 that's been left on night rate? Also put your ear against the cylinder, if its leaking on the outlet side you'll hear a faint continual hiss. Also look at the header pipe. It's normal to get a small overflow as it heats from cold to hot but it shouldn't be continuous. After that it's got to be checked by a sparks.

Mar 27 2020 01:05

Few more ideas.
Larger element and the fuse has popped?
The Control relay is playing up?
Has anyone actually checked the element is actually drawing current appropriate for the element size?
Had cable joint that has finally failed?
Had a customer years ago. 6 lights on and no problems. Turn on 1 more. Dull flickering lights. Was a burnt contacts in a porcelain fuse. The bit extra current was the tipping point. May be something similar with a larger element.

Mar 27 2020 09:00

Sounds like he's saying it heats to okay temperature by every morning but by afternoon it has gone cold again.

As others have said, it sounds very much like a leak and the overnight ripple-control fighting to reheat it all every night.

The power bill is going to be large.