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Topic Title: Charging efficiency of a modern storage heater brick pack
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Created On: 12 April 2013 04:52 PM
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 12 April 2013 04:52 PM
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AdrianRatter

Posts: 2
Joined: 16 May 2012

Hello,

Does anyone have a details of or a reference to information about
the time to charge a modern storage heater brick pack to the
thermostat set point.

I was also interested in comparisons between individual stand alone
heaters and centralised ducted air units.

Many Thanks
Adrian
 16 April 2013 05:06 PM
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normcall

Posts: 8178
Joined: 15 January 2005

As a long time fan of night storage heating, I might be able to point you in a direction or two.
Most stand-alone heaters rely on good insulation to bring the core up to maximum thermostat temperature within the specified time period.
Most modern heaters comprise of a steel sheathed folded element set, vertically mounted between refractory bricks and then insulated.
Older ones had a spiral element running horizontally backwards and forwards between a single groove in each of 6+ rows of blocks. The whole lot well insulated. My practical experience is that modern heaters are no-where as good as the older ones.

Centralised ducted air units.
In the 1960's , the electricity council did a lot of work on these units and I worked on two projects at that time.
Project one was a pair of Victorian cottages, installed with ducted air units, one was coal fired and one off-peak electricity (with afternoon boost). They were left in-situ for over a year and comparisons taken including ease of use, running costs and effectiveness.
Project 2 was a large commercial unit situated on the roof of a 3 storey office block. From memory, we struggled for months to get the thing to work using specially made stainless steel panels in an attempt to get enough heat into the air flow and duct into the offices below. I believe it was abandoned in the end as the core temperature could not be raised high enough without buckling the stainless steel.

I hope this information

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Norman
 21 April 2013 09:25 PM
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AdrianRatter

Posts: 2
Joined: 16 May 2012

Thank you for your reply.

I have found a fair amount out since my original post and managed
to come across an SSE study which tested a very recent design
of storage heater.

In short, both centralised air duct units an the latest stand alone
units have micro porous silica insulation with just a fair amount
more (at least 3x) in the centralised unit. Both have core temperatures
of around 600 deg C.

However, the physics of smaller cores and larger surface areas
mean the standing loss (no fan blowing) is about 2-2.5% of capacity per hour for the stand alone heaters and around 1% of capacity per hour for the centralised unit.

Efficiency favours the central unit.

Adrian
 22 April 2013 11:11 AM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

Efficiency favours the central unit


But distribution losses in a central unit may outweigh the initial impression of a saving when comparing central with distributed BSH units

Regards

OMS

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