Central Heating

[mikej460]

I'd be interested to know the actual figures in relation to expenditure for modernising, presuming their condemned boiler was very old.
My point being, sometimes the outlay takes decades to recoup in fuel savings. Double glazing isn't always the investment people think and loft insulation can take twenty years if you have to pay for it.
My system is open, modern pressurised systems would most likely require the replacement of the majority if not all of my system. Yes it would be cheaper to run, but at what cost to replace and maintain?! Modern boilers really can't last as long as much older versions and are often much less reliable.

Ah but we all have to go sometime, no matter how well we've performed in the past...

It really depends on the condition of your rads. If they're still ok but just need a flush then you might get away with you or the engineer/plumber removing them and flushing them outside. Converting to a sealed system is a straightforward re-piping job and removal of the header tank(s), we had this done at our last house.

 

[Jos7000]

I'm quite proud of my old boiler and will do as much as I can to keep it going (I'm a believer in bangernomics), it's a very early copper exchanger model. I used to work in a national callcentre that covered utility insurance and the horror stories associated with modern equipment put me off for life.
If it ain't broke... And if it is, fix it.

 

[croft36]

Our boiler specification states input 80,000btu/h, output 60,000btu/h which I interpret as 75% efficient?

 

[Jos7000]

Have you checked the pump efficiency yet? I swapped my pump as I bought a new one for £30, it changed my heating as previously cold radiators now get hot, the old one was still spinning up, just not working properly.

 

[stevek]

Were also running an old boiler, a Potterton Kingfisher, its an early one (30yrs plus as a guess) with a pilot light and cast iron heatexchanger, but its reliable and generally works fine and I really dont want to change it for a new boiler that friends and neighbours have found to their cost, are just plain unreliable, any savings in gas seem to be gobbled up by duff PCBs, callouts and fitters who often dont understand the bloody things themselves,,however our system is not the best, an 8mm microbore and now that this cold weather has arrived the system is struggleing and I wonder if this is the OPs problem? Were planning to keep going through the winter and see if we can give it an overhaul in the spring. The boiler is kettleing (bubbleing when running) so there will be sludge and scale in the boiler so my plan is to replace the pump, fit a magnaclean type filter on the return then run it for a few weeks with a system cleaner, then flush out as vigorously as we can with mains presure water. I doubt that it will be like new but Im hopfull it will improve matters.
Just as a matter of intrest, has the OP checked the flow and returns on the rads, Ive found hot flows and cold returns with rads barely warm,,somtimes a a blockage in the return pipe?

 

[Spectric]

The old pre condensing boilers with pilot lights did last a very long time, I have seen them over thirty years old and still going strong, albeit not super efficiently. Modern system boilers are generally more reliable than combi boilers, less complicated and work more leisurely. A combi to provide instant hot water goes through a lot of stress, rather like you being woken up with a bucket of cold water and then doing a long run. Well now they are looking to phase out gas boilers and make us all use electric or other sources, thats going to be very interesting. Everyone on electric heating with their electric car charging overnight, the old national grid will be groaning and adding to global warming.

 

[Jos7000]

The old pre condensing boilers with pilot lights did last a very long time, I have seen them over thirty years old and still going strong, albeit not super efficiently. Modern system boilers are generally more reliable than combi boilers, less complicated and work more leisurely. A combi to provide instant hot water goes through a lot of stress, rather like you being woken up with a bucket of cold water and then doing a long run. Well now they are looking to phase out gas boilers and make us all use electric or other sources, thats going to be very interesting. Everyone on electric heating with their electric car charging overnight, the old national grid will be groaning and adding to global warming.

This is actually the only acceptable route for me, I have a full bank of solar panels (16 in total) they really do make a difference, I installed back in 2011 so I get maximum return on the investment, but my inverter packed in two years ago and was I surprised when the electric bill arrived! The only thing preventing me going electric for my heating is the extortionate cost of buying the stuff. Everything for me is down to value versus longevity and modern things really do not cut it compared to the cost.

 

[Jos7000]

Were also running an old boiler, a Potterton Kingfisher, its an early one (30yrs plus as a guess) with a pilot light and cast iron heatexchanger, but its reliable and generally works fine and I really dont want to change it for a new boiler that friends and neighbours have found to their cost, are just plain unreliable, any savings in gas seem to be gobbled up by duff PCBs, callouts and fitters who often dont understand the bloody things themselves,,however our system is not the best, an 8mm microbore and now that this cold weather has arrived the system is struggleing and I wonder if this is the OPs problem? Were planning to keep going through the winter and see if we can give it an overhaul in the spring. The boiler is kettleing (bubbleing when running) so there will be sludge and scale in the boiler so my plan is to replace the pump, fit a magnaclean type filter on the return then run it for a few weeks with a system cleaner, then flush out as vigorously as we can with mains presure water. I doubt that it will be like new but Im hopfull it will improve matters.
Just as a matter of intrest, has the OP checked the flow and returns on the rads, Ive found hot flows and cold returns with rads barely warm,,somtimes a a blockage in the return pipe?

Take your radiators off one at a time and flush, shake, flush until you can't get any more crud out, flush the system after that leaving all the newly flushed radiators switched off to increase flow through the pipes. Be kind to your boiler though, if you blow the heat exchanger it will be game over for the boiler, unless you know someone who could fabricate a copy, preferably in copper.

 

[stevek]

Hi Jos,,electric is without doubt the future even without future legislation, we will look back on wet CH systems and wonder why we ever did it, my feeling is that you just pop along to Argos and buy a panel style convector heater, cost very little, no serviceing and if they go wrong you throw them away,,the only thing stopping us is the price of electric,,,I think there have been studies into the relative costs taking maintenence etc into account, and electric still comes out as more expensive,,however with a very well insulated house it might be different? Im assuming your high cost option is for storage heaters and using Off Peak electric?
Steve.

 

[stevek]

Take your radiators off one at a time and flush, shake, flush until you can't get any more crud out, flush the system after that leaving all the newly flushed radiators switched off to increase flow through the pipes. Be kind to your boiler though, if you blow the heat exchanger it will be game over for the boiler, unless you know someone who could fabricate a copy, preferably in copper.

Many thanks Jos, yep thats the general plan, anything to try and clear the crap out. If the boiler starts leaking were stuffed,,and it will have to be a new boiler, but it will be a sad day! Maybe there a new old stock Potterton laying around somewhere,,I should keep a eye on ebay!

 

[Jos7000]

Many thanks Jos, yep thats the general plan, anything to try and clear the rubbish out. If the boiler starts leaking were stuffed,,and it will have to be a new boiler, but it will be a sad day! Maybe there a new old stock Potterton laying around somewhere,,I should keep a eye on ebay!

You'd be lucky, at best keep an eye out for a decommissioned unit with intact exchanger. I've looked at mine and I doubt it would be too difficult for someone in the know to copy, they're not exactly special. A coil of pipe shaped to fit the boiler, with an alloy box to retain the heat and of course the fins. It's the pipes that bugga up, much of the rest could be recycled. Bearing in mind that mine isn't iron like yours. But the alloy box has the beginnings of a small vertical cracking which is being monitored. Luckily I know plenty of people with TIG welding setups.

 

[sirocosm]

I have an old Ideal classic with a cast iron exchanger, and a similar setup with a vented system and a vented cylinder (2 tanks in the loft), although my cylinder is not gravity fed. My system must be around 20 years old. I had a similar problem when I moved into the house, lukewarm rads, and lukewarm water. I took the head off the pump, and although it was working, the area around the impeller was full of crud, so I cleaned it out and it helped a bit. There was a thermostatic valve on the cylinder that was also seized so I took that out, which gave me hot water. Rads were still luke warm, so I took disconnected them one by one and used the hose to blow out blockages, which were not in the rads, but mostly in the microbore piping. After this I put in a jug of sludge remover and installed a magnetic filter. I could not believe how much sludge I emptied out of the filter over the next days, it was buckets. Over time all the rads, even the most distant ones are now working. I can only surmise that the previous owners did not use inhibitor, which I guess is essential for vented systems.

In my case when it was not working the boiler would not run very long, it would cut in and out. This is what I would expect if your system was blocked or the pump was weak. If the boiler is running continuously and the flow out of the boiler is still not getting hot, then I would suspect something wrong on the fire side.

 

[stevek]

I have an old Ideal classic with a cast iron exchanger, and a similar setup with a vented system and a vented cylinder (2 tanks in the loft), although my cylinder is not gravity fed. My system must be around 20 years old. I had a similar problem when I moved into the house, lukewarm rads, and lukewarm water. I took the head off the pump, and although it was working, the area around the impeller was full of crud, so I cleaned it out and it helped a bit. There was a thermostatic valve on the cylinder that was also seized so I took that out, which gave me hot water. Rads were still luke warm, so I took disconnected them one by one and used the hose to blow out blockages, which were not in the rads, but mostly in the microbore piping. After this I put in a jug of sludge remover and installed a magnetic filter. I could not believe how much sludge I emptied out of the filter over the next days, it was buckets. Over time all the rads, even the most distant ones are now working. I can only surmise that the previous owners did not use inhibitor, which I guess is essential for vented systems.

In my case when it was not working the boiler would not run very long, it would cut in and out. This is what I would expect if your system was blocked or the pump was weak. If the boiler is running continuously and the flow out of the boiler is still not getting hot, then I would suspect something wrong on the fire side.

Yes thats an anomily with the OPs post, the boiler is fired up and running but not producing heat?? That seems to be an impossible situation!

 

[Jos7000]

I wonder if the heat exchanger has come away from the pipes???

 

[croft36]

Have you checked the pump efficiency yet? I swapped my pump as I bought a new one for £30, it changed my heating as previously cold radiators now get hot, the old one was still spinning up, just not working properly.

We have concluded that the pump is not spinning. We will be sorting that and see where we are then and will keep you posted.
One thing we overlooked mentioning is that there is a mixing valve at the pump inlet! I always thought that these were only used to moderate the temperature in the storage tank, this one only affects temperature in the radiators!? I wonder if I should remove it?

 

[Jos7000]

I would leave that be.
It's a four way valve, I can't see how it's set, but they're designed to lower the temperature by mixing hot and cold together.
Unless it's actually doing that, in which case I'd be thinking about changing the setting.

 

[Glitch]

They certainly don't make them like they used to!

Must have put it there for a reason but can't understand why you heat water in your boiler (using boiler stat to set temp) then cool it down by mixing it with cold water. Makes more sense for the hot water cylinder where you want the water a bit cooler. Maybe it's just belt and braces.

Can you switch between Hot water and heating, or is hot water always on if heating is on?

 

[Jos7000]

Maybe the system has been altered in the past and it was just left in, perhaps the boiler was just overpowered when new. I believe underfloor heating can utilise lower temp heating.
I don't know anything about really old boilers, did they maybe not have internal stats and just keep belting out steaming hot lava??

 

[croft36]

I would leave that be.
It's a four way valve, I can't see how it's set, but they're designed to lower the temperature by mixing hot and cold together.
Unless it's actually doing that, in which case I'd be thinking about changing the setting.

It was seized when we moved in 42 years ago!

 

[croft36]

They certainly don't make them like they used to!

Must have put it there for a reason but can't understand why you heat water in your boiler (using boiler stat to set temp) then cool it down by mixing it with cold water. Makes more sense for the hot water cylinder where you want the water a bit cooler. Maybe it's just belt and braces.

Can you switch between Hot water and heating, or is hot water always on if heating is on?

Hot water is always on when Heating is on. The mixer valve only affects the heating water temperature. A pencil diagram of the system on the back of a circulating pump leaflet, presumably left by the plumber, indicates flows in the wrong direction in two instances, so he obviously knew what he was doing!!!!!