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The Renewable Heat Incentive
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adam2
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PostPosted: Tue Mar 08, 2011 4:21 pm    Post subject: Reply with quote

JohnB wrote:
vtsnowedin wrote:
If you have a gas wearedodgy range the top burners can be lit with a match when the power is off

I've heard that you can only get LPG cookers with electric ignition now, and can't light them without electricity. Not very helpful if you're off grid!


Simple electric ignition just replaces a match flame with an electric spark.
Can be used in a power cut by lighting with a match.
More complex systems use an electrical monitoring device to ensure that the gas is actually burning, these turn the gas off if it goes out. Requires electricity and cant be used without it.

Ovens commonly use an electric monitoring circuit and can not be used without it.
Top burners may have electric ignition, but the ones that I have seen can all be lit with a match instead.
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PostPosted: Tue Mar 08, 2011 4:26 pm    Post subject: Reply with quote

adam2 wrote:
JohnB wrote:
vtsnowedin wrote:
If you have a gas wearedodgy range the top burners can be lit with a match when the power is off

I've heard that you can only get LPG cookers with electric ignition now, and can't light them without electricity. Not very helpful if you're off grid!


Simple electric ignition just replaces a match flame with an electric spark.
Can be used in a power cut by lighting with a match.
More complex systems use an electrical monitoring device to ensure that the gas is actually burning, these turn the gas off if it goes out. Requires electricity and cant be used without it.

Ovens commonly use an electric monitoring circuit and can not be used without it.
Top burners may have electric ignition, but the ones that I have seen can all be lit with a match instead.


Yes, our lpg cooker is like that - so we only turn on the mains switch if we want to use the oven (the timer is useful too I suppose but I have a wind-up one which is nicer). Otherwise, a Swiss striking tool is used for lighting the hob.
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Bandidoz
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PostPosted: Tue Mar 08, 2011 4:54 pm    Post subject: Re: The Renewable Heat Incentive Reply with quote

An Inspector Calls wrote:
heat pumps have no forum listing

I've expanded "Geothermal" to encompass Heat Pumps (and moved this topic to there).
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PostPosted: Tue Mar 08, 2011 4:58 pm    Post subject: Reply with quote

kenneal wrote:
In energy terms you might as well be using gas direct as, with the efficiency of generation, you would be using less energy for the amount of heat given than you are to generate the electricity.

That's assuming that gas is used to generate the electricity. Heat pumps *could* be a useful dump load for grid balancing (e.g. like the LTS systems - http://www.powerswitch.org.uk/forum/viewtopic.php?t=2102 ).
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PostPosted: Tue Mar 08, 2011 5:41 pm    Post subject: Reply with quote

adam2 wrote:
Ovens commonly use an electric monitoring circuit and can not be used without it.
Top burners may have electric ignition, but the ones that I have seen can all be lit with a match instead.

So not much use off grid then. Some of the people who were discussing it were trying to find one suitable for off grid use.
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adam2
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PostPosted: Tue Mar 08, 2011 8:13 pm    Post subject: Reply with quote

Bandidoz wrote:
kenneal wrote:
In energy terms you might as well be using gas direct as, with the efficiency of generation, you would be using less energy for the amount of heat given than you are to generate the electricity.

That's assuming that gas is used to generate the electricity. Heat pumps *could* be a useful dump load for grid balancing (e.g. like the LTS systems - http://www.powerswitch.org.uk/forum/viewtopic.php?t=2102 ).


I have my doubts as to the suitability of heat pumps for use as a dump load or for grid balancing.
A heat pump is a substantial investment and is most unlikely to be worthwhile unless used as the main heat source and run near continually when heating is required.
If only used when there is a surplus of power it will probably never repay the capital costs.
A better bet in most cases is natural gas for heating, rather than burning the gas in a power plant and then useing a heat pump.
If surplus wind power is available at very low cost, but for limited hours a year, then an electric boiler could be automaticly turned on instead of gas when required.
Electric boilers are cheap simple appliances, and produce water as hot as required unlike heat pumps.
The surplus wind power would of course have to be sold at a lower price than gas for this to work.
Only a limited number of electric boilers could be installed in the same area without costly upgrades to infrastructure.
Hospitals and hotels often use a great deal of gas for space and water heating, fitting electric boilers to such premises could use surplus windpower when available, with gas still being burnt at other times.
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kenneal - lagger
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PostPosted: Tue Mar 08, 2011 8:58 pm    Post subject: Reply with quote

adam2 wrote:
Hospitals and hotels often use a great deal of gas for space and water heating, fitting electric boilers to such premises could use surplus windpower when available, with gas still being burnt at other times.


Hospitals are horrendous wasters of fuel. The temperature is often too high, the insulation is inadequate, the proportion of glazing is often too high and not shaded on south and west elevations leading to overheating and there are usually no local heating controls, again leading to local overheating. With a little expenditure huge amounts of money could be saved for the NHS.

Hotels are not getting the idea yet, either. I stayed in a not very expensive (cheapish) hotel in Rio de Janeiro a few years ago and they had room switches to turn every thing off when you took your key card out of the slot and lighting on every floor was controlled by proximity sensors. You won't often find that in even expensive hotels in Europe.
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cubes



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PostPosted: Tue Mar 08, 2011 10:40 pm    Post subject: Reply with quote

A lot of hospitals are hot for a reason though - seriously ill people feel the cold a lot more than healthy ones. Whether the entire hospital needs to be that warm though...

adam2 wrote:

Ovens commonly use an electric monitoring circuit and can not be used without it.


Couldn't the manufacturers fit a small gas generator into the system somewhere? I doubt it would need to provide a great deal of electricity.
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vtsnowedin



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PostPosted: Wed Mar 09, 2011 2:42 am    Post subject: Reply with quote

cubes wrote:
adam2 wrote:

Ovens commonly use an electric monitoring circuit and can not be used without it.


Couldn't the manufacturers fit a small gas generator into the system somewhere? I doubt it would need to provide a great deal of electricity.

Stoves built before about 1960 used pilot lights to light both the top rings and the oven and broiler burners. These work perfectly well but wasted the fuel used to keep the pilots burning between uses of the stove. There is no good reason other then big brothers desire to make everything fool proof to not have gas appliances that are match lite(if the electric power is off) on every burner which would both save fuel and be as safe as anything we have today.
I have an old pilot type stove up in my hunting camp. It works as good as new. In a little while I may be able to sell that stove for more then the camp is worth.
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An Inspector Calls
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PostPosted: Wed Mar 09, 2011 9:45 am    Post subject: Reply with quote

kenneal wrote:
An Inspector Calls wrote:
The energy I'm now wasting is solar energy that I've extracted from the adjacent field using a heat pump. That energy would have simply been lost if I hadn't extracted it. In other words, I have my own energy farm. What is only relevant is the amount of energy I have imported, and that is on a par with PassivHaus. Where the imported energy came from is as relevant in the heat pump case as it is would be for PassivHaus.
I'm not on the gas grid.


You are using additional energy to power the heat pump. With Passivhaus levels of insulation you wouldn't be using any energy at all to heat the house most of the time.
PassivHause uses additional energy to heat water and run the heat exchangers. It's the same thing.
kenneal wrote:
A stone house would give tremendous thermal mass which, if warmed during the summer, could heat the house well into the winter

The corollary being that the house would then be cold well into summer! No thanks.

kenneal wrote:
You're assuming that the next fifty years will be like the last fifty years. A grave mistake.

I'll take my 'chance' that you're wrong (I shan't sleep nights).


Last edited by An Inspector Calls on Wed Mar 09, 2011 10:16 am; edited 1 time in total
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An Inspector Calls
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PostPosted: Wed Mar 09, 2011 9:51 am    Post subject: Reply with quote

adam2 wrote:
An Inspector Calls wrote:
[
The grid event you refer to was not a rota cut. It was a low frequency incident as is obvious from the title of the report:
"Report of the investigation into the automatic demand disconnection following multiple generation losses and the demand control response that occurred on the 27th May 2008"

The cause is well described therein:
"On the morning of 27th May an unrelated and near simultaneous loss of generation at Generator A (345MW at 11.34am) and Generator B (1237MW at 11.36am), totalling some 1582MW at the time of loss, gave rise to a drop in system frequency to 49.14Hz. Following this there was a further, as yet not fully explained loss, which led to a further drop in system frequency to 48.795Hz."

All very coy! Generator A was Longannet, B was Sizewell, and the "further, as yet not fully explained loss" was the wind fleet tripping because of low frequency.
.


I can not agree that the event described was not a rota cut.
Owing to the unexpected failure of two large generating units, the grid frequency fell to well below normal levels.
To prevent the frequency falling any more, a percentage of the load was automaticly dissconnected by low frequency relays.
Not enough power to go around, some load cut off. Sounds to me like a rota cut, even if only for part of one day.
It could happen again, but should be a rare event.
Regular rota cuts are unlikely but could occur, perhaps as a result of a severe shortage of natural gas, as might be caused by turmoil in the M/E.

The event you referred to was a grid system failure, a low frequency event. NONE of the load shedding that occurred after the final generation trip was pre-managed according to a written rota, but was actually done by grid-attached, automatic load shedding relays. The event was serious enough to cause transport disruption. No one in the country had any knowledge of where the cuts would occur, or when they would happen. That ain't a rota.

My idea of a rota would be something like the earlier events you referred to during the miner's strikes, when pre-published areas of the UK were warned, and experienced planned, timetabled disruptions to supply. The rota cuts would be planned to avoid sensitive supply points like hospitals and transportation.


Last edited by An Inspector Calls on Wed Mar 09, 2011 10:02 am; edited 1 time in total
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An Inspector Calls
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PostPosted: Wed Mar 09, 2011 9:56 am    Post subject: Reply with quote

Bandidoz wrote:
kenneal wrote:
In energy terms you might as well be using gas direct as, with the efficiency of generation, you would be using less energy for the amount of heat given than you are to generate the electricity.

That's assuming that gas is used to generate the electricity. Heat pumps *could* be a useful dump load for grid balancing (e.g. like the LTS systems - http://www.powerswitch.org.uk/forum/viewtopic.php?t=2102 ).

I think you're right. If we had a full implemenation of a Smart Meter concept, which would inform the customer when prices were low during a generation surfeit, then you could programme a heat pump to take advantage of those price opportunities. Most heat pumps are actually ready fitted with the technology to do this. I can't connect this facility on mine, because there's no relevant input! In the case of Danfoss (Swedish heat pump) that's how they're operated in Sweden, I think.
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adam2
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PostPosted: Wed Mar 09, 2011 10:24 am    Post subject: Reply with quote

I feel that some posts are confusing electric ignition of a gas flame with an electricly powered flame failure sensor, or an electricly operated gas valve.

Electric ignition, or ignition from a continually burning pilot light may be replaced by use of a match or lighter.

Electricly powered flame failure sensors or electricly operated gas valves cant be used without electricity. This can of course be obtained from a battery and inverter, but that adds complication, expense and another point of failure.

Older types of gas burning appliance sometimes used a self powered flame failure device. This consisted of a thermocouple heated by a pilot light, the heat of the flame produced electric current which was used to hold the gas valve open. If the flame went out, or failed to ignite, the gas valve would shut. This worked well, but had 2 drawbacks.
Firstly the power produced was minute and could not possibly open the gas valve, this had to be done manually normally by holding in a button for perhaps 30 seconds until the thermocouple produced enough current to hold the valve open. This was beyond the understanding of many users.
"Hold red button down firmly, push ignition button until flame lights, continue to hold red button down for at least 30 seconds, then release. If flame goes out, try again this time holding in for longer"
Not that hard, but widely disliked, and therefore not much used these days
The other drawback was that if the flame blew out, it could take 30 seconds for the gas valve to shut. In that time enough gas could escape to be dangerous in an enclosed oven or boiler.

Portable bottled gas heaters still use such a system, but for fixed appliances it has fallen out of favour.
One touch electric ignition and flame failure monitoring is the norm for ovens.
Boiling rings are normally electricly ignited, but without any flame failure device, they may therefore be lit with a match in a power cut.
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PostPosted: Wed Mar 09, 2011 10:40 am    Post subject: Reply with quote

The electric ignition failed on our (8 year old) gas hob last month.

We now use a peizo-electric (sp?) hand held lighter. Or matches.
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Bandidoz
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PostPosted: Wed Mar 09, 2011 12:54 pm    Post subject: Reply with quote

An Inspector Calls wrote:
kenneal wrote:
A stone house would give tremendous thermal mass which, if warmed during the summer, could heat the house well into the winter

The corollary being that the house would then be cold well into summer! No thanks.

It doesn't work like that - it prevents the house becoming too hot during the summer. Basically the extremes of hot and cold during a daily cycle are damped by the thermal inertia.
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