Hot water cylinder using a lot of power

Forums › Home Workshop DIY › Hot water cylinder using a lot of power

Jase2985

13772 posts

Uber Geek
+1 received by user: 6254

ID Verified

Lifetime subscriber

#251330 19-Jun-2019 13:43

Good Afternoon All

We have a Rheem 180L Mains Pressure Vitreous Enamel heater that was installed about 7 years ago. This has been great for us, but its starting to use about 6kwh+ of power when its heating the water. Looking back at our power it seems to have started in early to mid few and its power usage has been slowly growing and growing to where it is now.

Yes it most definitely is the hot water cylinder, i have done a heap of testing using my power monitor, and is has a 3kw element installed.

I take it its the element thats stuffed and ill need to get another one installed?

Thanks in advance.

1 | 2 | 3

20923 posts

Uber Geek
+1 received by user: 5395

Trusted

Lifetime subscriber

#2260883 19-Jun-2019 13:55

What did your plumber say?

Zeon

3927 posts

Uber Geek
+1 received by user: 759

Trusted

#2260885 19-Jun-2019 13:55

I'm not advocating this as a solution but if you got a transformer of 230v to 110v would that halve the heating on a resistive element?

Speedtest 2019-10-14

Jase2985

13772 posts

Uber Geek
+1 received by user: 6254

ID Verified

Lifetime subscriber

#2260889 19-Jun-2019 13:58

timmmay:

What did your plumber say?

good question, but plumbers dont deal in electricity

MadEngineer

4644 posts

Uber Geek
+1 received by user: 2619

Trusted

#2260892 19-Jun-2019 14:01

Electrician will measure resistance of the element and replace if need be.

You're not on Atlantis anymore, Duncan Idaho.

Jase2985

13772 posts

Uber Geek
+1 received by user: 6254

ID Verified

Lifetime subscriber

#2260893 19-Jun-2019 14:02

it was fine and using 3kw of power when heating the water, up till mid few when the power usage started increasing to where it is now at about 6kw when heating the water.

Zeon

3927 posts

Uber Geek
+1 received by user: 759

Trusted

#2260895 19-Jun-2019 14:07

But what is the issue? Won't you get warmer water faster or you don't have enough amps for the rest of the house?

Speedtest 2019-10-14

Apple TV

Stream your favourite shows now on Apple TV (affiliate link).

Rikkitic

Awrrr
19157 posts

Uber Geek
+1 received by user: 16483

Lifetime subscriber

#2260897 19-Jun-2019 14:11

What is your water supply like? We have very hard spring water and our elements regularly burn out. When that happens it can increase the load for awhile.

Plesse igmore amd axxept applogies in adbance fir anu typos

wellygary

8931 posts

Uber Geek
+1 received by user: 5466

#2260907 19-Jun-2019 14:30

It could also be the Thermostat, (i.e its now heating the water almost all the time, rather than switching off when it gets hot,)

(Often your neighbours will notice this before you do, as they will see steam and hot water belching out of the expansion pipe (usually on to the roof)

Dynamic

4037 posts

Uber Geek
+1 received by user: 1862

ID Verified

Trusted

Lifetime subscriber

#2260916 19-Jun-2019 14:37

It sounds like an odd situation... if the element is 'partly short circuited' so a smaller portion of it is getting twice as hot and using twice as much power, I'm a little surprised this isn't tripping the breaker/fuse as that's 25A running through the cable. I'd guess that the breaker would be 15A or maybe 20A. I know there is a bit of a tolerance, but still.....

I'd chat to a Sparky about replacing the element, just in case there are unexpected negative consequences to leaving it in the 'partly faulty but still working' state.

If you own the property, you can replace it yourself if you have the necessary skills: https://worksafe.govt.nz/managing-health-and-safety/consumers/safe-living-with-electricity/getting-electrical-work-done/doing-your-own-electrical-work/

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

Jase2985

13772 posts

Uber Geek
+1 received by user: 6254

ID Verified

Lifetime subscriber

#2260922 19-Jun-2019 14:51

wellygary:

It could also be the Thermostat, (i.e its now heating the water almost all the time, rather than switching off when it gets hot,)

(Often your neighbours will notice this before you do, as they will see steam and hot water belching out of the expansion pipe (usually on to the roof)

nope, its a mains pressure so no expansion pipe. and its defiantly switching off. Heats for about 10 minutes every 6-8 hours when not being used to maintain temp. its done that since we got it. its just now using 6kw peak to heat it instead of 3kw peak.

Rikkitic

Awrrr
19157 posts

Uber Geek
+1 received by user: 16483

Lifetime subscriber

#2260924 19-Jun-2019 14:52

Dynamic:

It sounds like an odd situation... if the element is 'partly short circuited' so a smaller portion of it is getting twice as hot and using twice as much power, I'm a little surprised this isn't tripping the breaker/fuse as that's 25A running through the cable. I'd guess that the breaker would be 15A or maybe 20A. I know there is a bit of a tolerance, but still.....

I'd chat to a Sparky about replacing the element, just in case there are unexpected negative consequences to leaving it in the 'partly faulty but still working' state.

If you own the property, you can replace it yourself if you have the necessary skills: https://worksafe.govt.nz/managing-health-and-safety/consumers/safe-living-with-electricity/getting-electrical-work-done/doing-your-own-electrical-work/

There are definitely consequences. The last time our element didn't completely burn out, just kept drawing more and more current. I knew something was going on from funny background noises but didn't twig for a couple of days. That's what fuses are for, right?

Eventually I realised something major was going on. This is an old farmhouse with old everything. There are two switches for the cylinder, one in the cupboard, the other on the main board. When I touched the one in the cupboard, it left a burn scar on my hand. I immediately cut the power.

Further investigation revealed that both switches were burned through and had melted internally. So what about that fuse? We have the old wire variety. When I checked it, I discovered that some genius (who clearly knew enough to be dangerous) had brilliantly replaced the fuse wire with steel wire. It probably could have gone to a hundred amps before it would have blown. The calcifying elements were a recurring problem so this idiot no doubt thought he was being clever. I had to replace both switches, which were burned through, but fortunately the wiring had not melted. It has been fine in the years since and we have added a rainwater tank for the hot water to prevent the problem recurring.

Plesse igmore amd axxept applogies in adbance fir anu typos

Lego

Shop now for Lego sets and other gifts (affiliate link).

Jase2985

13772 posts

Uber Geek
+1 received by user: 6254

ID Verified

Lifetime subscriber

#2260927 19-Jun-2019 14:55

Zeon:

But what is the issue? Won't you get warmer water faster or you don't have enough amps for the rest of the house?

its a 3kw element, thats the issue, it shouldn't be using 6kw.

+ old wiring

Dynamic

4037 posts

Uber Geek
+1 received by user: 1862

ID Verified

Trusted

Lifetime subscriber

#2260931 19-Jun-2019 14:58

Wow, @Rikkitic that sounds like a very near miss with a fire. And if it happened late at night when everyone is sleeping.... *shudder*

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

Rikkitic

Awrrr
19157 posts

Uber Geek
+1 received by user: 16483

Lifetime subscriber

#2260945 19-Jun-2019 15:21

Yeah, I was completely freaked when I discovered it. Clearly it had been like this for years. Our farmhouse would literally go up like a torch. The interior walls are old rimu planks, not gib. We cut some out when remodelling and it burned like it was impregnated with accelerant. Very old and dry.

Plesse igmore amd axxept applogies in adbance fir anu typos

Aredwood

3885 posts

Uber Geek
+1 received by user: 1749

#2260964 19-Jun-2019 16:21

Have you checked the pressure relief valves? As the most common fault that causes excessive power usage by a hot water cylinder is faulty valves, that cause hot water to be continuously discharged to waste. Since you have a mains pressure cylinder, there definitely will be a drain pipe from those valves somewhere. Have seen people make raised gardens against the side of the house, and then bury the outlet. (garden gets watered with hot water). Or the pipe just discharging onto the ground underneath the house.

Leaking hot water pipes will have the same effect.

Of course, maybe you are just using more hot water now. Have you checked your water meter? Does it say that something is using water that shouldn't?

Very rare for an element to develop a fault that would cause it to draw more power, but not blow the fuse. And even if it did, the cylinder will simply reheat faster. And there wont be much difference to total power usage.

1 | 2 | 3