Electric Radiators V LPG central heating.

[ban-all-sheds]

But get hot water, and a CoP of 3, and with our climate - lets just say I'm 'a tad sceptical'.

The thing is you need hot water, boiling water even, all the year round, and the percentage of the time where the outside air is so cold as to drive the COP down to pointless levels is actually quite small.

In this country, if you have a mains gas supply, then on cost grounds you will not beat a decent condensing boiler properly installed so it does actually condense.

Which AIUI means replacing your radiators if the system was designed for standard boilers.

 

[JohnW2]

In this country, if you have a mains gas supply, then on cost grounds you will not beat a decent condensing boiler properly installed so it does actually condense.

Which AIUI means replacing your radiators if the system was designed for standard boilers.

Eh? Why should the type of boiler have any effect on the type of radiators? All radiators know is that hot water is being pumped through them - they have no knowledge of, or interest in, how that water became hot.

... or am I missing something?

Kind Regards, John

 

[JohnW2]

In this country, if you have a mains gas supply, then on cost grounds you will not beat a decent condensing boiler properly installed so it does actually condense. I believe the economics are different if you are using LPG.

LPG certainly is now very expensive. I don't have the figures to hand to enable me to do a comparison with natural gas by calorific value, but LPG is now well over 50p per litre (costs me well over £1,000 to fill my 2,000 litre tank).

Kind Regards, John

 

[ban-all-sheds]

Eh? Why should the type of boiler have any effect on the type of radiators? All radiators know is that hot water is being pumped through them - they have no knowledge of, or interest in, how that water became hot.

... or am I missing something?

Again qualified by "AIUI", you need the return water to be low enough for the boiler to go into condensing mode, so unless you want to be hotter all the time you need the flow temperature to be lower as well. So basically the whole system runs cooler so you need larger radiators at a lower temperature in order to get the same heat out of them.

AIUI the reality of condensing boilers is that we are all forced to have them, at significant extra cost, because of their theoretical better performance when in practice they hardly ever deliver that performance. They are a monumental con foisted on us by people with vested interests lobbying Government officials who did not understand the issues.

Remind you of anything?

Unfortunately that particular bit of pointless cost imposition is a lot harder to ignore.

 

[ericmark]

We are now getting the same with wood burners hence campaigns like this one stop burning our trees. Not sure they have got all the facts correct but with the removal of wood left to rot by wood stove owners the woodland is being damaged by users of wood stoves. Also the particular emissions are a problem with the cheaper stoves where there is no heat store so the stove is banked down rather than run hot. The Energy Saving Trust say a wood stove system costs around £11,000 to install and a system costing that will likely be efficient and not produce particular emissions but many fitted do not have that system.

There are also super gas boilers which sterling engines which produce electric from the waste heat and pump it back into the grid (if not used in house) the same way as solar panels. From what I am told British Gas is the only installer at the moment.

Again installation costs are huge. The condensing boiler has had loads of problems with the condensate freezing and boiler closing down in cold weather and also lock shield valves not being set correct so on start up very slow heating the house. Not a fault with system just bad installation. Again should have a by-pass valve and TRV on ALL radiators often fitted like old system with some radiators without TRV and a thermostat (electric) in that room so the two systems fight each other for control.

It seems there are some very good ideas but that's all they are. "Ideas" they are not being implemented as the design calls for they are just botched together and then people wonder why they don't work.

It seems I can have an electric light and a electric heater but am not allowed to combine them into one unit tungsten bulbs are out even though the alternative is filled with mercury or arsenic. We stopped using mercury in batteries then used it in light bulbs instead.

If you want to reduce heating bills the way forward is to retain the heat already in the house rather than allow it to escape. These

heat recovery systems do seem to work but are so big to retro-fit is hard.

It's not easy to select the best. I am glad I don't have to.

 

[cliff1010]

Thanks for all the advice I do think we will go over the spec for insulation and still have time to think about type of heating

Cliff

 

[bernardgreen]

Many years ago a friend's father took the engine from a wrecked Mini and converted it to run on gas. This drove a generator to power heaters and lights with the engine cooling system heating water. It ran for several years and was cost effective compared to using gas in a then standard boiler.

I agree that condesnsing boilers need larger radiators ( or fan assisted heaters ) to get the highest overall efficiency. It is nice to feel flu gases that are barely warm to touch from a well designed system..

 

[JohnW2]

Again qualified by "AIUI", you need the return water to be low enough for the boiler to go into condensing mode, so unless you want to be hotter all the time you need the flow temperature to be lower as well. So basically the whole system runs cooler so you need larger radiators at a lower temperature in order to get the same heat out of them.

Ah, I didn't realise that - must do some reading. As Bernard has pointed out, fan-assisted radiators would presumably be an alternative to large ones. However, in keeping with what you say, I've never heard of anyone changing their radiators when they have been forced to change to a condensing boiler.

Kind Regards, John

 

[ericmark]

Beware of fan assisted radiators I have one on old system and yes it does work well but there is no restriction on water flow. Can't really throttle back water flow as required flow will change according to fan speed set and it the thermostat has started the fan or not. Sending hot water back with an old system was not a problem however with new system it would reduce or stop the boiler output.

Also they are noisy specially at night when watching TV I have to up the TV volume when fan starts. Not that much noise but at night tend to have sound as low as I can.

I suppose they could be piped is series rather than parallel like in large buildings schools ect. But who thinks the plumbers will get it right? They don't seem to be able to set lock shield valves so setting up a Myson think your asking a bit much.

Heat up times are great. No sooner has the central heating cut in and the fan is blowing out warm air. However so is the cooling down time within minutes of central heating switching off the fan has stopped.

So we had to add a standard radiator to keep the room warm between batch runs of the boiler. The condensate type boiler has variable output rather than a batch run but as I have said I can't find any conversion which will allow the Myson to run with a boiler whose output is controlled by the temperature of the return water.

The standard radiator system should shut off each radiator as that room becomes warm forcing more water around radiators in the cool rooms until the pressure of all radiator TRV closing opens the by-pass valve and the hot return water shuts down the boiler.

But with the Myson once one room is warm the fan stops so hot water is returned prematurely shutting down the boiler. I am told with just one Myson it will work OK that the hot water return will no affect the boiler too much when mixed with the rest but putting hand on return pipes on my boiler I can't see that being the case.

 

[EFLImpudence]

You do seem to live in a complicated world , eric.

 

[SimonH2]

Eh? Why should the type of boiler have any effect on the type of radiators?

Again qualified by "AIUI", you need the return water to be low enough for the boiler to go into condensing mode, so unless you want to be hotter all the time you need the flow temperature to be lower as well. So basically the whole system runs cooler so you need larger radiators at a lower temperature in order to get the same heat out of them.

Exactly right.
For the boiler to run, most systems need a bypass in order to keep the flow rate through the boiler up to some minimum level - and often this is just a gate valve not a pressure relief type. AT full heating load it shouldn't be too bad, all the rads will take flow, and they'll lose a lot of heat. As heat load reduces (the room warms up), the TRVs throttle back, and the proportion of water going through the bypass valve increases. At some point, the boiler is getting back hot water.
Condensing boilers only condense when the return water temp is below about 54˚C. So if you have an old system with rads sized for high flow and return temps, you'll not be condensing for a lot of the time.

If you increase the size of the rads, you can reduce the flow temperature, and thus reduce the return temperature. IIRC from last time I looked at rad sizing, dropping from 50˚ to 40˚ mean delta T halves the heat output of a rad ! 50˚ might be 80˚ in/60˚ out and 20˚ room temperature. 40˚ could be 70 in/50 out. The former will never let the boiler condense, the latter will much of the time.

That's one reason I like a thermal store - you can run the boiler how the boiler needs to run, and the rad how the rads need to run (all TRVs, no room stat, fully modulating pump).

AIUI the reality of condensing boilers is that we are all forced to have them, at significant extra cost, because of their theoretical better performance when in practice they hardly ever deliver that performance.

Indeed, the system needs to be re-designed for them to work effectively. Modern boilers are complex and unreliable comapred to the older ones - but it has to be said that if the system is designed correctly they will save a fair bit of gas.

They are a monumental con foisted on us by people with vested interests lobbying Government officials who did not understand the issues.

Well I may well agree there !

Many years ago a friend's father took the engine from a wrecked Mini and converted it to run on gas. This drove a generator to power heaters and lights with the engine cooling system heating water. It ran for several years and was cost effective compared to using gas in a then standard boiler.

Well we may well see that sort of thing come back - and with exhaust heat recovery as well. All thanks to the renewables lobby and politicians (and officials) buying into their emperor's cloths stories of how good those darned windmills are.

A year or two ago I was at a local engineering society talk given by someone well involved in smart metering technology. The stories he told us of political ineptitude were "quite alarming". But the key thing is that the main reason for smart meters is nothing to do with efficiency - if you need to do a load of washing it'll use electricity whether you do it at 6pm or 2am ! They are all to do with what can best be described as rationing by stealth. When we've shut down our end of life nuclear stations, and it's become too expensive paying the fines for ignoring the EU rules telling us to shut down the coal stations, then the only thing left will be reducing demand to match supply - so when the wind drops or gets too strong and the windmills are doing f**k-all, the lecky cost will rocket and people will elect to ration their usage (those without deep pockets will, those with deep pocket (say a cushy job in Westminster with gold plated pension and expenses rules we couldn't even dream of) will be able to carry on. If that isn;t enough, then the other key element will kick in and we'll have power cuts - just done on a house by basis instead of by district as some of remember from the 70's).

But I digress ...
Sat next to me was a lecturer from the local college - he was already looking into diesels with heat recovery and reckoned they are fairly efficient. So whether gas or diesel, I think we'll start to see a few more embedded generators going in soon.

 

[cliff1010]

What a lot of advice, I have taken it all in and thinking this granny anexe is for my mother in law who likes to be warm as all old folk. She will more than likely have the heating on in the summer, we will go down the LPG boiler route.

The reason 1, we have LPG already I still need to talk to Calor and see if they can take another supply from our existing tank.
2, when you look at the cost of the radiators I was quoted £1000 for 3
I have seen the boiler for less than that yes I have the install but I feel the boiler option will also give us a better re sale value if we ever move on.

Once again thanks for all the advice.
Cliff

 

[JohnW2]

...we have LPG already I still need to talk to Calor and see if they can take another supply from our existing tank.

Engineering-wise, I'm sure there is no problem with taking multiple feeds from one tank, provided that tank is deemed to have enough capacity for the total 'load' - my LPG tank certainly serves several 'loads'. I would imagine that any problem is likely to be administrative/legal, depending on the extent to which the granny annexe is seen as part of the same dwelling. If it were regarded as something separate, which could come into separate ownership, a 'shared tank' might be seen as a potential problem.

Kind Regards, John

 

[cliff1010]

Fair point John, but to get the planning permission I had to have a section 106 legal document made up so the annexe it tied to the main house as one dwelling. With this I hope to get away with the connection, as my mother in law wants to pay her way do you know if you can get a meter to tell how much she has used. Or is this then getting down the separate dwelling route.

Cliff

 

[JohnW2]

Fair point John, but to get the planning permission I had to have a section 106 legal document made up so the annexe it tied to the main house as one dwelling. With this I hope to get away with the connection, as my mother in law wants to pay her way do you know if you can get a meter to tell how much she has used. Or is this then getting down the separate dwelling route.

I'm sure that one can get gas meters (just like those used in standard natural gas installations) that could measure the amount of gas that had flowed down one pipe. I'm no lawyer, but if you've got is all legally constituted as a single dwelling, then I would not have thought there would be a problem - and I don't think that having a meter (within your pipework) would make any difference to that (indeed, I'm not even sure that Calor would necessarily even need to know about it!). I imagine that Calor's main concern would be that they had a contract with a single person (you) who would be responsible for paying all their bills!

Sure, I suppose there is a possibility that the 'single dwelling' could be 'split' at some point in the future - but that's true of almost any dwelling which has an LPG supply, so I wouldn't think that would be a problem, either, if it's definitely a 'single dwelling' now. However, in the final analysis, Calor are obviously the only people who can tell you what their attitude/approach is!

Kind Regards, John