Storage heater replacement options

[zoothorn]

10 minutes ago, A_L said:

 Leave the damper in an open position and wait for the next off peak period to see if it closes automatically.(have the input control set to a small value).

 

 

Ok this is getting complicated now. damn. Right, how does it close automatically?

[zoothorn]

43 minutes ago, dpmiller said:

No, a TRV is liquid or wax filled just like the thermostat in a car.

 

But this is what I know/ I know a TRV is on a rad filled with nothing other than water.. but regardless of whether a rad's liquid is water, wax or oil.. the principle remains that the valve introduces a wallop of heat every now & then via a thermostat = a hot rad, or a cold rad if the room is deemed warm enough.

 

I'm not sure how this answers my Q's.

[A_L]

1 minute ago, zoothorn said:

Ok this is getting complicated now. damn. Right, how does it close automatically?

 

When the storage rad is energised the resistor heats and the heat transfers to the bi-metallic strip which 'flexes' because the two metals expand at different rates, the bi-metallic strip will be attached to the flap and the flexing causes the flap to close.

[zoothorn]

@A_L can you explain to me what this 'energised' state is. I understand the principle of store > release.. but the basic construction I see is 4 heating elements surrounded by bricks (roman-simple) with a control circuit to turn the elements on & off. How can these elements be asked to 'energise' the bricks, or whatever gets energised?

 

Where does this 'energising' situation physically occur?

[SteamyTea]

Energized just means it is getting electrical power.

The power for night storage heaters is from a separate circuit and is switched on and off by a radio signal receiver in the main meter.

There are some very old systems that still have mechanical timers, but not many left now.

Edited June 19, 2019 by SteamyTea

[zoothorn]

Ok SteamyTea.. but once its got electric power from a separate circuit switch, understood.. what happens? I'm trying to understand this 'energised' state. Something must get energised. I understand that it is by electricity only.

 

I assume that the bricks are what get energised- is that correct? if so, how?

[dpmiller]

8 hours ago, zoothorn said:

 

But this is what I know/ I know a TRV is on a rad filled with nothing other than water.. but regardless of whether a rad's liquid is water, wax or oil.. the principle remains that the valve introduces a wallop of heat every now & then via a thermostat = a hot rad, or a cold rad if the room is deemed warm enough.

 

I'm not sure how this answers my Q's.

 

As I previously said, the *STAT* is a wax or oil powered analogue device and does NOT slam open and closed as you describe.

 

[ProDave]

Storage heaters are in fact very simple devices.

 

They contain a load of bricks that store heat.  Inside the stack of bricks are a number of electric heating elements.

 

The electric feed to the storage heaters is fed via some form of tine switch so the electricity supply to the heaters is only on at night when it is charges at the cheap rate.  So at night the electricity heats the bricks.  It does this until the cheap rate ends and turns off, or the bricks reach a certain temperature, in which case an electrical thermostat (the right hand knob) turns them off.

 

During the day, the electricity to the heaters is off and all they are doing is letting out the stored heat in a controlled manner.  This is controlled with the left hand know that opens or closes the flap to allow heat out, or not.

 

That flap should automatically be closed during the overnight charging.

 

 

[zoothorn]

2 hours ago, dpmiller said:

 

As I previously said, the *STAT* is a wax or oil powered analogue device and does NOT slam open and closed as you describe.

 

 

 

Ok sorry I misunderstood your post before then. I can't make head nor tail of wax/ oil thermostats- its too technical, but it doesn't matter.

 

All I know is the TRV rad I had, & ones I knew in a C.heating before this house (usefully, only a stove & 2 fan heaters to think of here!).. were, during their 2 hour PM heat slot, either in a flat-out very hot state, or in a stone-cold state. I assume therefore this correlates with the TRV tripping them on, then off (which in turn, to me means this TRV is fundamentally a 0/1 switch).

 

Can you shed any light?

[zoothorn]

52 minutes ago, ProDave said:

Storage heaters are in fact very simple devices.

 

They contain a load of bricks that store heat.  Inside the stack of bricks are a number of electric heating elements.

 

The electric feed to the storage heaters is fed via some form of tine switch so the electricity supply to the heaters is only on at night when it is charges at the cheap rate.  So at night the electricity heats the bricks.  It does this until the cheap rate ends and turns off, or the bricks reach a certain temperature, in which case an electrical thermostat (the right hand knob) turns them off.

 

During the day, the electricity to the heaters is off and all they are doing is letting out the stored heat in a controlled manner.  This is controlled with the left hand know that opens or closes the flap to allow heat out, or not.

 

That flap should automatically be closed during the overnight charging.

 

 

 

Hi Prodave- that's a nice clear summing up, just what I needed. Useful for my folks should they read this too.

 

Ok there's one thing I can't understand. This 'charge' process. It -must- be, looking at the few internal components/ relative simplicity of these StHtrs.. that during the night, the elements heat the bricks. There's nothing else in there that could power/ charge anything, bar the elements.

 

So, if these elements are powering/ charging > heating these bricks.. bricks get hot > so the rad gets hot > so, the room gets hot. At night.. I don't want the room hot. So how is this system viable? just putting a thin metal flap on top of the gap between bricks.. cannot mean they become a lower temperature, just the heat is trapped a bit more; the heat will still conduct thru this 1mm steel strip & up/ out anyway in 5 mins.

[SteamyTea]

7 minutes ago, zoothorn said:

just the heat is trapped a bit more; the heat will still conduct thru this 1mm steel strip & up/ out anyway in 5 mins.

The strip reduces the airflow to almost zero, so no convection happens.  The rest of the heat is insulated, so little is lost (they are warm to the touch, but not hot.

So a small strip can reduce the overnight heating.

Assuming that storage heaters are not faulty, they work incredibly well.

 

As an aside, check your parents water heater.  There are two elements usually, one at the top and one at the bottom.  If the top one is switched on it can heat water anytime of the day or night.  This gets expensive.  Ideally just the bottom heater should be on as this is the Economy 7 one.  It heats the water during the night and even if you only use water during the day, it does not get thermally recharged until the next night (usually between midnight and 7 AM, though this can be different in different areas).

If you can read the meter, post up the numbers and that gives a fair bit of information.  There should be 3 readings t= total, 1=day and 2=night.  If you can also see the date the meter was installed (often just crayoned on the meter) then that is also useful.

Some more modern and key meters give more information, but it should be fairly clear what is what.

Edited June 20, 2019 by SteamyTea

[dpmiller]

14 minutes ago, zoothorn said:

 

 

Ok sorry I misunderstood your post before then. I can't make head nor tail of wax/ oil thermostats- its too technical, but it doesn't matter.

 

All I know is the TRV rad I had, & ones I knew in a C.heating before this house (usefully, only a stove & 2 fan heaters to think of here!).. were, during their 2 hour PM heat slot, either in a flat-out very hot state, or in a stone-cold state. I assume therefore this correlates with the TRV tripping them on, then off (which in turn, to me means this TRV is fundamentally a 0/1 switch).

 

Can you shed any light?

 

Yes. Two hours wasn't long enough...

When you turned the heating ON the room was either too hot or too cold. Ergo no heat or lots of, in the rad. If you'd left the heating on for longer (and also assuming the rads were all set up with the correct Delta T via the lockshield, as should've been the case but probably wasn't...) then as the room approached the setpoint of the TRV flow would have reduce and thus the Delta T across the rad.

The adjustment of a TRV to set room temperature is pretty subtle.

[zoothorn]

1 hour ago, ProDave said:

 

 

@dpmiller Ok "Delta T's" are meaning understanding is getting even more elusive/ complicated.

 

Ok can I just ask another way. Say the 2 hour PM slot was 4 hours instead. During this period, the house Cheating is timed to go on. During the start of it the rads trip on, & get the room up to 18* & above. Then the rad trips off, the room after 10 mins goes down to 17*. The rad trips on.

 

This I know to be fact & makes some sense, by way of restricting the ammount of time the rad is on for = efficiency.

 

But the result in my case, from my direct experience, is the rads are either in a flat-out hot (when trv is tripped on).. or a stone cold state (when trv is tripped off). This is a pain in the ass: too hot to touch, & nasty for a child for eg, or stone cold. Why can't a heater just produce a medium heat instead, for twice the length of time? THIS is my point. THIS would determine my choice of a whole house heating system. Just WARM rads please.. not OTT hot / stone cold (1 / 0.. a switched rad, surely it can be called). But a C.heating system cannot give me this afaict.

[zoothorn]

17 minutes ago, SteamyTea said:

The strip reduces the airflow to almost zero, so no convection happens.  The rest of the heat is insulated, so little is lost (they are warm to the touch, but not hot.

So a small strip can reduce the overnight heating.

Assuming that storage heaters are not faulty, they work incredibly well.

 

 Ok this is making more sense now, air flow considered. And the tips re. water tank etc helpful.. Mum?? you reading this? (I gave her the thread link.. but likely she'll ignore it or fall asleep).

 

Still I'm trying to understand this night period. I understand its at a lower £rate, the principle. But if 4x elements are producing heat, to get trapped within bricks around them, during this time.. how can this heat NOT be transferred out from the rad during this time? just a 1mm strip of metal with alot of heat below it will conduct heat thru > up & out. And so how can the stored energy do anything other than pretty quickly diminish as a result? If the flap was a whopping ceramic hat sealed to perfection.. ok. But it always the very opposite: a wobbly thin bit of metal without any specificly designed sealing edge to it at all afaict.

[SteamyTea]

1 minute ago, zoothorn said:

just a 1mm strip of metal with alot of heat below it will conduct heat thru

It does, but as the area that strip covers is small, not much heat escapes.

It is really to do with stopping the convection, not radiant heat.  A radiator is really a convection heater.  They would have to be glowing to radiate a decent amount of heat (opinion is divided here, but that is another subject).

Just take it as read that this small, think strip, does stop most of the heat escaping during the charge up period.

 

[zoothorn]

Ok Mr.Tea.. I'd have to assume also that the elements are on a 'low' output at this time? do the elements act like cooker ones & can be adjustable, or are they doing the on/off (flat out on/ totally off) intermittant thing I wonder (that I hate)? the reason I ask is just back to the symptoms of my folks' one: flat out baking hot rad at midnight.

 

Also the galvanised sheet across the whole face of the heater under the cover.. is this to actually -trap/ prevent- heat from getting out, rather than acting like a conductor to facilitate radiated heat out from the large panel face-?

[A_L]

27 minutes ago, zoothorn said:

I'd have to assume also that the elements are on a 'low' output at this time? do the elements act like cooker ones & can be adjustable, or are they doing the on/off (flat out on/ totally off) intermittant thing I wonder (that I hate)? the reason I ask is just back to the symptoms of my folks' one: flat out baking hot rad at midnight.

 

 

Storage radiators charge at only one rate from the start of the charge period till the core reaches the temperature corresponding to the input control setting. They then passively give off heat till the start of the next charge period

 

Perhaps this will help:

 

 

[zoothorn]

Thanks for that @A_L ok that's all clear on the charge process. As to the release system then: what is this 'input' dial then, separate from the flap open-close dial (I think this is the boost dial)?

[SteamyTea]

In input dial limits the maximum temperature that the bricks get to.  The higher the temperature, the more energy is stored, but also the more losses.  But it does mean that more power can be delivered.

There is generally a sweet spot for storage heaters.  I set mine so that both dials are at 6 (half way).  If I know we are in for a few days of extra cold weather, I turn the input one up.

warmer weather, I turn it it down.

Sometimes I forget, but soon realise and can then adjust with the output (flap) knob.

[zoothorn]

So its called input bc it regulates the 240v coming in > which means the 'charge' is varied by this?

 

Can you set the 'release' periods to two 2-hour slots AM & PM.. or once the charge period ends/ release period starts, it just releases steadily throughout say 8AM to 11PM? & can you vary the ammount of release?

 

The more I look into these things the more complicated they're becoming! started off a simple circuit + 4 elements + flap ontop.

[SteamyTea]

4 minutes ago, zoothorn said:

Can you set the 'release' periods to two 2-hour slots AM & PM

If you mean automatically set it, then no.  They are very basic electro-mechanical devices.

Thing is, you should not need to.

First things to check is that all the elements are working, then just set the two dials in the mid position.  See what happens.

I know this is not the time of year to do this, but it can wait until the right time as any repairs should be easy and quick.

Or just replace them.

https://www.tlc-direct.co.uk/Type/_Heaters.StorageHeaters.html

Edited June 21, 2019 by SteamyTea

[zoothorn]

Actually ST I'm not asking from a repair pov (could 100% fix a stuck flap or change an element, 80% replace the WW resistor) I'm just trying to work them out for me, & maybe for my folks. If they can't use a tv remote to get to iplayer, or to remove subtitles (auto get shoved up/ no idea how to undo.. so watch tv with them over screen).. there's little chance they know what the 'input' or 'boost' dials are for. Actually I still don't know what the input dial is for, from a user pov.. bc 'input' means nothing to a user. I'd think 75% of owners have no idea why the word's on one of two dials they're meant to control their comfort with.

 

Is the word input on the 2nd dial bc it regulates the voltage up/down for the charge process? how is this word useful to the user? why not 'heat 0-10'?

[SteamyTea]

3 minutes ago, zoothorn said:

I still don't know what the input dial is for, from a user pov.. bc 'input' means nothing to a user.

This limits the maximum temperature that the bricks get to (generally on older storage heaters).  It is done via simple thermostat that just cuts the power.  The reason that it is there is because it is impossible to have a storage heater that is perfectly sized.  By limiting the brick temperature, the total amount of thermal energy stored can be controlled.

So say you need 12 kWh of energy stored, but you can only get storage heater in 10 kWh and 15 kWh, turning now the input control, a 15 kWh store can be reduced to 12 kWh.

10 minutes ago, zoothorn said:

I'd think 75% of owners have no idea why the word's on one of two dials they're meant to control their comfort with.

If only it was that low, I suspect that 95% of users have no idea how to set them.  That is about 6.5 million people that fell asleep during science lesson at school.

[zoothorn]

So, could this input dial be called as it were 'heat output' then? I'm still confused as to why there's a dial called input, that's one of two for the user. If I explained what you have to me above, to a user, 99% wouldn't have a clue what you are talking about (me included- I cannot understand kWh).. so they, & me have no idea still what the dial is -practically- for.

 

First I thought these were design simplicity, now I'm thinking they're design lunacy.

Edited June 21, 2019 by zoothorn

[SteamyTea]

20 minutes ago, zoothorn said:

So, could this dial be called as it were 'heat output' then?

No, because it is the input.

 

There are two main things that govern the performance of a storage heater, the energy stored, which is in kWh and the power they can deliver, which is measured in kW.

Think of it as a box of hot stones.  The greater the number of stones in the box, the more energy is stored, that is the kWh's.

If you take a stone out you are delivering power, power is kW's.

So dividing the kWh by the kW, gives you the amount of time that the stored energy can be delivered.

So varying the the amount of energy in the store, the kWh, by adjusting the the input, also changes the amount of time you can deliver power for.  If you only have 1 kWh stored and you deliver power at 1 kW:

1 kWh / 1 kW = 1 h

 

Sometimes this is hard to understand because the units kW and kWh are so similar sounding, even people that used them day in and day out often get them muddled.

It really comes down to SI units and there derived units.

SI units are things like metres, seconds, kilograms.

From these we get derived units.  These have symbols and names such as J for joule, W for watt...

A J is a unit of energy and derived by multiplying mass, in kg, by distance, in metres.

A watt is a joule divided by time, in seconds, so J / s = W.

This can quickly lead to very large numbers, energy is often in the millions or larger, giga, tera multipliers.

One thing done to reduce these large number is to change the number of seconds into an hour.  There are 3600 seconds in an hour.

 

(I may have not explained that too well, ask @Ed Daviesas he has something up on his website about it)