# Stiebel Eltron Electric Storage Heating



## Mountain Electrician (Jan 22, 2007)

Up this way heating costs for next winter are a hot ticket item and I recently had a service call to inspect the heating system for a large "ski camp" at a local resort. I was told the camp used either oil or gas space heaters, and they wanted me to make sure they were all working properly and efficiently. I told the HO I could verify that the electrical hook ups were correct and up to code, but I wasn't qualified to make recommendations concerning the heaters themselves. 

When I arrived at the camp, I found that what they have is an electric storage heating system that was manufactured in Germany by a company called Stiebel Eltron and installed in 1983. The house has 2 separate services, one 200 for the camp, and a 400 (320) for the heating. There are (17) 2 and 3 KW space heaters throughout the camp with individual t-stats, and a main controller to interface with the POCO. The system seems pretty simple: The heaters consist of elements that heat bricks during off peak times, and then discharge the heat as needed. 

Is anyone familiar with these systems, and if so what are some of the problem areas to look for? I wonder how cost efficient they really are, I guess I'll have to find out what the POCO is charging for the off peak power, and what the efficiency of the 25 year old heaters are. The company still makes there types of heaters, and their web site says they are backwards compatible and more efficient than ever. 

http://www.stiebel-eltron-usa.com/pdf/brochure_ets.pdf

So, if anyone has experiences they can share with these Stiebel Eltron heaters, I would really appreciate it. I want to make as an informed recommendation as I can.


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## jfwfmt (Jul 5, 2008)

*I had a very similar system in my previous house*

The system consisted of three parts:

main control box
individual storage boxes
room thermostat associated with each storage box

The main control box had
input from the KWH meter - an off peak closing contact
input from an outdoor thermometer
input from some override switches
output consisted of a circuit to all storage boxes. This circuit energized resistors placed near the thermostat INSIDE the storage box. When energized, it opened the thermostat, preventing heat storage during on peak.
output was the water heater circuit which was off during on peak unless the WH override switch was on 
output was control circuit to 250V 50A spa water heater which was off during on peak unless the SPA override switch was on
output was power to several bedroom baseboard strip heaters which was off during on peak
[output was contact closure which I used to control on/off peak KWH meters on my PV circuit]
The control box had a circuit that attempted to modulate the off peak storage time based on the outdoor temperature. This was usually a bit dodgy during spring and fall. It also had jumpers that affected this modulation.
The override switches were momentary contact which provided a limited time override, maybe 1 hour.
The relays were all solid state.

A Storage box consisted of heaters, bricks, thermostat, fan and above mentioned resistor. There may be a klixon over temperature protector and a pilot light indicating either overtemp (or storing?). The internal thermostat controls the max temperature stored and was adjustable from the outside with a knob. The fans in the storage box are controlled by the room thermostat. If the box runs out of heat and the room is still cold, it blows cold air.

I never had problems with the storage boxes or room thermostats. Several years after initial installation, the control box was replaced under warranty or recall, at no cost to me.

The heating system (and PV) were installed under a peak shaving program from National Grid with them paying a part of the cost of each.

Unfortunately I left the manuals with the system so this is all from memory.

/s/ Jim WIlliams


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## jfwfmt (Jul 5, 2008)

Electric resistance heaters have 100% efficiency
we had a 14/04 cent on/off peak rate


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## Mountain Electrician (Jan 22, 2007)

Jim, thanks for the input! That sounds like exactly the same system except this one has no spa output. 

As far as efficiency, my question is this: while the conversion of electricity to heat in the bricks is 100% efficient, is there any loss transferring heat from the bricks to the room? It would seem the longer you store the heat the more likely you are to lose some of it. 

I'm going to contact the manufacturer tomorrow, and go from there.

Thanks again.

Jed


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## DPDT (Nov 3, 2007)

Vet here of a lot of storage unit installs and service calls. I'll tell you right off the bat that the Steibels are not among my faves. Replaced alot of fan boards, seperate home runs for the fans on some units and not very well built. On new installs I only use Steffes. Superior in every way.


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## Mountain Electrician (Jan 22, 2007)

DPDT said:


> Vet here of a lot of storage unit installs and service calls. I'll tell you right off the bat that the Steibels are not among my faves. Replaced alot of fan boards, seperate home runs for the fans on some units and not very well built. On new installs I only use Steffes. Superior in every way.


Got a hold of Steibel who referred me to a third party and all they have is parts, they aren't making the heaters any more. I was told that Steffes are the only man. of ETS's in the world now. (???)

I can rebuild a Stiebel for @550.00 in parts, or buy a Steffes for around 1500.00. But I also have to but a new controller for 1000.00, and then run parallel controllers and change the Stiebels out as they fail. I think I'll recommend rebuilding the Stiebels as they have lasted 25 years, with new parts maybe they will last 25 more. :thumbsup:

Probably not.


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## DPDT (Nov 3, 2007)

The Steffes use PLC (Power Line Carrier) to broadcast orders to the individual heaters. The PLC box has the OTS installed with the appropriate chip for designing and altering the heating curve. If you want individual heaters to run together as a zone you can run an 18/3 between each unit and an external thermistor to keep them in sync. We've installed everything from their individual storage units to their 45kW hydronic systems. I took a course from them this spring just to check out new products and it was pretty informative. They gave me software for troubleshooting, tech docs, and some sales tools as well.


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