Storage Heaters

[Andy]

I think electricians get worried about too much..
If the load is less than 13amps get it plugged in!
I think Joe is doing a great job!

I totally agree with Joe doing a great job and I'd hate to stop him. I've taken a lot of inspiration from everyone here over the years and I love hearing the stories and adventures unfolding.

Its just some things come with unexpected pointy edges that could make your day a bad one. Previously I worked on the fact that I could do what I like on a 32 A ring. It turns out you have to do so with caution.

[chris_n]

I think electricians get worried about too much..
If the load is less than 13amps get it plugged in!
I think Joe is doing a great job!

My self applied rule is 10A or less continuous rating. 13A is fine for sporadic loads but can start to get warm over time especially with sprung contacts like a socket. Having said that I do know what loads are already on the various circuits and where they sit on the ring.

[nowty]

Those small storage heaters are typically 850W, so less than 4 amps.

[Joeboy]

Those small storage heaters are less than 4 amps.

The best thing about this bit of the conversation is that there WILL be someone out there who reads this and has an 'aha' moment on his/her own build.

[Andy]

Those small storage heaters are typically 850W, so less than 4 amps.

I really thought you'd have been pulling a lot more as a combined load. I've been quite surprised.

[Caesium]

Just fiddling with my new units As expected they're very simple and very old; the smaller one has 2 heating elements at 850W each, the larger one 4.

The output dial literally mechanically moves a metal plate to create an airway out of the insulated chamber so the warm air can rise out, or closes it so it can't. This is a bit simple for me and I'm worried that rooms will either always be too warm or too cold. So retrofitting a fan.. somehow.. that I can control with a thermostat will be a high priority I think. I just need to find something that will fit in the space and not melt with what could be pretty hot air coming out. Wonder if anyone has suggestions on what sort of thing to look for, I suppose I wouldn't mind them just being cable-tied to the outside of the grille if they had to be..

Not sure how the input works yet, there must be some sort of thermostat on it so it takes into account residual heat from the previous nights heating; if I rotate it I can see the resistance across it (its inline with the power to the elements) suddenly change from 0 to 1MOhm, so effectively turning them on or off. I guess the higher this is set, the hotter the bricks end up being.

[Stinsy]

I do think the point about continuous vs intermittent loads requires consideration. A kettle or similar high-power short-duration load doesn’t seek out the weaknesses in your wiring in the same way as a continuous load.

The first thing to bare in mind WRT SH (and other continuous loads) is the power. A 1kW SH isn’t as much of a worry as a 3kW one.

The next is the quality of the connections. A hardwired FCU is best, but we like smartplugs around these parts and they require a plug and socket. It is worth fitting a new high quality plug and socket if the ones you have are old or of undetermined quality. I like MK Logic sockets, Haygar Solysta are highly regarded too. If you have a high-power SH (2.4kW or more) you might want to consider a dedicated circuit with a smartplug-controlled contactor.

A dedicated circuit for each SH is obviously the ideal scenario. But you could say that about any device, and we don’t live in an ideal world. We need to apply common sense, understand the dangers and take steps to mitigate them.

[Oldgreybeard]

Cool, I thought of going down your route but got told off by my electrician. He does that regularly when I come up with new ideas. Hopefully it is good info for those without the knowledge.

There are a few "golden rules" that some often get confused about. The rating of fuses is a good one. The absolute maximum continuous current that a "13A" plug can tolerate is 10A, about 2.3kW. Any more and it will overheat and eventually fail, usually by scorching around the live pin from the heat from the fuse. Same goes for any fuse, the maximum that a 100A main fuse can run at continuously is 65A, same reason, it will get hot if run at any higher current for a long time.

The plug problem is largely down to changes made to the design. The older 13A plugs were fine at 13A continuously, but the safety mafia changed the design and added insulation around the pins, so that people couldn't wrap their fingers around them and touch them by accident. This insulation thinned down the pins a lot where they enter the plug, and this reduces the ability of the plug to carry a high current for long periods, or more accurately limits the heat dissipation rate.

Bloody stupid that the powers that be didn't tell the general public about this, but it is a VERY well understood failure mode within the electric car fraternity, where overheating plugs is such a problem that manufacturers are putting heat sensors into them to shut down chargers.

I believe Stinsy is spot on, this is a continuous load problem, and one that only appears with high current (over about 2.3kW) loads, and high current loads have got less common in the last few years, with the reduction in the power of appliances.

[Joeboy]

Just fiddling with my new units As expected they're very simple and very old; the smaller one has 2 heating elements at 850W each, the larger one 4.

The output dial literally mechanically moves a metal plate to create an airway out of the insulated chamber so the warm air can rise out, or closes it so it can't. This is a bit simple for me and I'm worried that rooms will either always be too warm or too cold. So retrofitting a fan.. somehow.. that I can control with a thermostat will be a high priority I think. I just need to find something that will fit in the space and not melt with what could be pretty hot air coming out. Wonder if anyone has suggestions on what sort of thing to look for, I suppose I wouldn't mind them just being cable-tied to the outside of the grille if they had to be..

Not sure how the input works yet, there must be some sort of thermostat on it so it takes into account residual heat from the previous nights heating; if I rotate it I can see the resistance across it (its inline with the power to the elements) suddenly change from 0 to 1MOhm, so effectively turning them on or off. I guess the higher this is set, the hotter the bricks end up being.

I leave doors open and just let the heat circulate. The thermostat is a bi metal sprung unit for make/break. The spring tension being carried at the right hand knob. The lower you set it the higher the tension so it breaks quicker (I think).

[AE-NMidlands]

The plug proble is largely down to changes made to the design. The older 13A plugs were fine at 13A continuously, but the safety mafia changed the design and added insulation around the pins, so that people couldn't wrap their fingers around them and touch them by accident. This insulation thinned down the pins alot where they enter the plug, and this reduces the ability of the plug to carry a high current for long periods, or more accurately limits the heat dissipation rate.

Bloody stupid that the powers that be didn't tell the general public about this, but it is a VERY well understood failure mode within the electric car fraternity, where overheating plugs is such a problem that manufacturers are putting heat sensors into them to shut down chargers.

actually a friend of mine was on the committee which agreed this... Have you ever heard of anyone getting a shock from putting their fingers round a plug? I'm not sure it has ever happened.
The real story is that when we got decimal new pennies, kids quickly found that one would fit perfectly between the 3 pins, so schools were crippled by a spate of circuits tripping, and as fast as you found which plug had a penny between it and the socket another had been sabotaged!
Hence the redesign of plugs to prevent it. Reading the comments above I reckon it would have been better to have had special "School plugs."