New Gas Boiler

[guest27]

HI All

Nowt to do with thumpers...

Had the boiler repaired again yester day and the plumber asked whether we had thought about replacing the boiler rather than having it fixed all the time.  First off he is not punting for work....  He is a good guy if somewhat busy.

We have an old Ideal Mexico (100,000 btu), which I guess is not the most efficient of boilers, heating a large detached house.

If we were to look at thins what should we be thinking of?  A quick chat with Tony suggested a good quality conbi boiler - but having a look about I can see that there are combis and combis, and condensing boilers and others etc etc.

I know a number of you have more knowledge of all of this than I have - what sort of questions should I be asking in relation to finding a good outcome - hot house, hot water, low bills, low CO2 print (or tending to all of those)

Ta

R

[Steve H]

Rog, one of my plans is to replace our boiler with a combi which can take pre-heated water. The idea is to have solar collectors (on the garage) pre-heat the water in a tank before passing into the boiler which would 'top up' the temperature. From memory you need a water tank which can withstand mains pressure and so they are not cheap. Doesnt answer your question but might be worth considering when choosing a boiler.

[Bill Rutter]

I had to replace our combi 18 months ago in the middle of a cold snap. We were told that condensers were pretty much the way to go nowadays. It cost £1600 to have a BAXI one fitted by a CORGI registered fitter. We heard all manner of stories about how we could have got one for less but on closer inspection the money we paid was about right really. You will save money by getting a new one. A poorly boiler just wastes energy. And you just know the one you have will fail you just when you are in from afreezing ride and all you want is a hot bath. Those three days without a a decent hot water supply were murder. We ended up with a "wheelie-bin"-type contraption in the bathroom to give us  hot bath water.

[guest27]

Glad there are also some other strange people on here too - I was wondering if I could fit a mains pressure stainless tank before the boiler to preheat water in solar panels...

Brilliant minds


Saw a thing called the tadpole the other day - a tank that 'removes' the gas from water before it goes into the boiler - anyone know anything of these?

R

[johnr]

rog, if youre fitting a new boiler, thenit will have to be a condensing boiler, you dont really have any choice in it!, from experience, i would say fit a worcester bosch, theyre probably the best of the bunch, and whilst you may have to pay a bit more to fit them, they pay for themselves in the long run with their reliability. i have seldom had to go back to a worcester that ive fitted, theyre the last word in reliability, and when we move to our new house in a few weeks, i'll be fitting one there. the solar hybrids idea is nothing new. basically you fit a set of solar panels on the roof, and feed these to a mains pressure hot water system9also known as an unvented hot water system) the panels will heat the water in the tank, this then feeds down to the boiler, and goes in the cold inlet side of the boiler. the idea being that if the water is hot enough, the boiler senses this and just lets the water through, but if the water isnt hot enough, the boiler kicks in and boosts it up to the required temp. its a major investment though, as the combi, cylinder and panels are all expensive items on their own. if your house is an old one, it is always worth looking into topping up your insulation, as the amount you can save by propperly insulating can easily exceed the amount you save by fitting a new boiler. current regs iirc call for between 9 and 12 inches of insulation in a loft!!

[Steve Lake]

With regard to the solar heated input....I use a standard copper cylinder (which comes with urethane insulation) it is ok for mains pressure (this may depend on your local pressure, it's pretty low here, and this cylinder is in the garage, so it's not a disaster if it leaks! ), the solar panels run into the indirect loop of the cylinder, thus i can run a mixture of fernox and antifreeze through them without contaminating the rest of the system...the indirect loop has a pump, controlled by a temp sensor, such that when the panel temp exceeds the tank temp the pump runs. and as previously stated, the output of this cylinder feeds the main system, the boiler only coming on if the main system needs hotter water than is being supplied by the auxilliary input tank (such as at night and cloudy days).
I'm currently using home made panels (old steel single panel radiators, painted matt black, in an insulated box with a tripple wall clear plastic/poly top) these work tolerably well, but nowhere near as well as the evacuated tube systems now available, but at £400 per panel (well, thats the best price i can find) i'm not in a position to go down that route yet, mind you, if oil keeps going up, i may have to.

[guest27]

Steve

What sort of temp does the rad-solar panels acheive in the water - is it worth the effort of making?  Do they warm any on winters days?

All

Any thought about the boilers with a Stirling Engine in the flue - seem to remember a lot of fanfare about them and then nothing.  Are they as good at that!  lol

Thanks for the input and keep it coming please.

R

[johnr]

With regard to the solar heated input....I use a standard copper cylinder (which comes with urethane insulation) it is ok for mains pressure (this may depend on your local pressure, it's pretty low here, and this cylinder is in the garage, so it's not a disaster if it leaks! ), the solar panels run into the indirect loop of the cylinder, thus i can run a mixture of fernox and antifreeze through them without contaminating the rest of the system...the indirect loop has a pump, controlled by a temp sensor, such that when the panel temp exceeds the tank temp the pump runs. and as previously stated, the output of this cylinder feeds the main system, the boiler only coming on if the main system needs hotter water than is being supplied by the auxilliary input tank (such as at night and cloudy days).
I'm currently using home made panels (old steel single panel radiators, painted matt black, in an insulated box with a tripple wall clear plastic/poly top) these work tolerably well, but nowhere near as well as the evacuated tube systems now available, but at £400 per panel (well, thats the best price i can find) i'm not in a position to go down that route yet, mind you, if oil keeps going up, i may have to.

no, you need to use a mains pressure cylinder, theyre usually stainless steel, and come with an expansion vessel on top, as the heated wqater needs to have somewhere to expand into, they also need to be fitted with any number of non return valves and pressure relief valves and also temp relief valves. in sohort, no, you cant use your existing cylinder. i cant begin to say how many water byelaws you will be contravening, not least the risk of a tank full of potentially boiling hot water bursting inside a house or garage.

however, theres a slightly more budget way of getting in on solar, try looking up a panel called "solartwin" this can be piped into existing systems, and connected directly into the hot water cylinder, and on the direct side too, not the indirect. the panel is devised in order to allow it to freeze up in winter, and then thaw out and still work ok. fially, the solar twin has a small photovoltaic panel built into it, this powers a pump that circulates the water from tank to panel, as its photovoltaic, it only works when the sun shines, so you dont waste heat at night by pumping your hot water round a solar panel on a dark roof. this  system means you dont need to modify an existing cylinder fed hot water system too much to get the benefits of solar.
the payback time of a full solar system may be around 20+ years, but as energy prices rise, it makes more sense. i may well be fittng a solar panel when we move house, but im in the plumbing trade, so im not subject to the usual crippling installation costs.


i think anyone interested in this technology who wants to see how to do it on the cheap would find a trip to CAT (centre for alternative technologys) in wales well worth their while. they even run residential courses on how to build you own panels.

[guest27]

Thanks for that John R

I have the CAT DIY book on solar panels and may follow that route - but as you say as fuel prices rise....

Whilst I have to pay installation costs we have a very good local plumber - callout and fixing the pilot tube on the old boiler £10 - cannot argue... mind you have to be happy to leave the house open as he is liable to turn up at 2 in the morning on his way home from another job.

Will only work for GC this - but he was here late one night - fixing the same problem which is why we are thinking of looking at another boiler rather than throwing money at this - and he got too low on our drive and backed his van over the bank on the edge - spent a couple of hours around midnight on Friday looking for sober mates with 4X4s to come and pull him off.  But at least he remembers where we are.

Will talk this load over with SWMBO

Similar thoughs - have a book on green buildings here and it mentions hydrothermic floors - not the std type with the pipes a few inches below the surface but running solar heated water through a 6' thick block of sand / concrete etc to heat it up over the summer to leak heat over the winter.  Now it strikes me digging a 6" hole under my house is liable to see the whole lot fall into the hole.  Any thoughts on how to insulate the area around the house so the heat does not conduct away with out having to dig a big hole - so I will not fill the hole with terracotta sand (the best for heating*) but we are on very rocky sub so not too bad.

R

* it is all to do with the wave length of the radiation and thus why water filled steel rads need to be hotter for a given level of comfort to cast iron ones - or better still terracotta blocks...

[Steve Lake]

John of course is right.....but i'm not hampered by making my living from plumbing......and i wouldn't ponce about with anyone elses setup, if it bu55ers up, then I shall have to do the job properly, maybe get john in:-)

with regard to the home made panels....they put out heat in any sunlight, winter or summer.....but not much in just bright daylight. unlike the new vacuated black tube type....which chuck out heat in any weather.

but at least mine prove the system works...and when i can afford the pukka ones I will get some.

[johnr]

im not touting for work steve! i work for a large energy management company doing industrial/commercial heating and plumbing maintainance, so im not really after any more work, i gave up on foriegners as we called them some years back. like you said, its your system so your problem. just dont tell the insurance company or the neighbours!! id reccomend a pressure vessel though, they arent dear, in fact if you were closer, ive one you could have. its just a safety thing really, when water wants to expand, theres not a lot you can do to stop it!!

[johnr]

this is an interesting forum, ok, its setup by a panel manufacturer, but the stuff in it is pretty generic, and its pretty new, but, its got some handy installation diagrams showing pipe layouts etc and is handy for anyone who may want to figure out how to lay out a system.

http://www.solarsavings.co.uk/forum/viewtopic.php?f=11&t=7

[johnr]

Similar thoughs - have a book on green buildings here and it mentions hydrothermic floors - not the std type with the pipes a few inches below the surface but running solar heated water through a 6' thick block of sand / concrete etc to heat it up over the summer to leak heat over the winter.  Now it strikes me digging a 6" hole under my house is liable to see the whole lot fall into the hole.  Any thoughts on how to insulate the area around the house so the heat does not conduct away with out having to dig a big hole - so I will not fill the hole with terracotta sand (the best for heating*) but we are on very rocky sub so not too bad.

this may interest you, not quite what you want, but its handy info if you dont want to dig under the house!!!!


http://www.nrel.gov/docs/fy04osti/36277.pdf

[Steve Lake]

Thanks for the offer john.....no i wasn't after you doing a 'foriegner'  (the same name for it in my job as well )

well, the guy who bought my SRX #3 is a plumber (strangely...called John....) and he has pressure vessels and all that stuff.

As i have just fitted a new header tank in the loft....i may use that as the supply for the secondary tank and the indirect loop as well, not ideal, lots more pipes etc, ther's so many ways to organise it, especially as i'm not pushed for space.....probably going to go through many many arrangements before i get it right :-)

[guest27]

John, again, thank you very much.

R