Hi,
20 year old Potterton Kingfisher II. (& 20 year Hot water cylinder)
Open Vented system.
Before you say, I am considering new condensing boiler but costly to change (BG wanted £4700) & till now absolutley 100% reliable, have read quite a lot of problems with newer boilers so not so committed.
Sorry very long winded post but hoped the more info the better.
No port valves or tank stat. so HW always ON with CH.
No problem with actually hot water flow from taps, problem is in the primary.
Central Heating works well. 16 rads get hot, some very (balanced & some TVR's) 5 bed house warm.
If I turn CH off, hot water does heat up, albeit quite slow now but will get to 70 degrees. I emptied for 1st time till cold running through & took nearly 3 hours to get to 60+ degrees, so guess this not quite right. However, normally have some v.hot still left in cylinder seemed to recover in 1-2 hours so not really noticed before.
Soon as I turn heating on & pump starts HW does not heat up & might even loose a little temperature. Rads get warm pretty quick.
Primary to cylinder not pumped and goes into loft towards header, branches off before & down to radiator in bathroom (always hot)
This bathroom radiator also fails to heat or retain heat in the same way the HW cylinder does when central heating is engaged.
I assume perhaps some sort of air lock or perhaps is there something in the boiler itself that favours the flow to the CH and starves the primary F&R.
Air Lock, I don't see where this could be, if in cylinder surely it would rise up the coil & eventually out the vent (Vent is above water level & header fills & empties fine) I also assume not in cylinder as pipe above cylinder input (going to vent) cools also. Also when only HW & working would this not push air out. Been like it for week now. Can you get air lock in the bolier itslef?
If I hold the primary flow pipe (When cooled a bit) I can feel what seems a little like bubbling, plop... plop 5 or 6 times in a minute, but not sure if just water movement or pump/bolier vibration.
There is a fitting 12" from boiler on route to cylinder & on, looks like some sort of valve, T piece but just a couple of nuts on the top with 8mm 'ish hole in it, quite furr'd up with limescale
Have empied & filled dozens of times during my 20 years with it & never had any issues refilling, rad's bleed easily & reliably.
Quite a soft water area but kettle will get pretty bad in a few years.
Gas bills have been bad, even before the cold spell, 30-50% up but with price increases and so many estimates its hard to tell. £200 per month, CH on 24/7 @ 19 day & overnight & 20 degrees when occupied.
Now, Have I caused this !!
A few months back I put a new digital room stat. in place of old dial. Great piece of kit, different temps at time of day etc etc.
However, I wonder if it keep heating cyling longer than before, doubt it but hey, trying to cover all bases.
Pre snowy, v cold snap I thought system could do with a clean. Not being very cold before perhaps would not have noticed if it was working as during normal climate, room stat goes off reguarly giving hot water time to recover.
Anyway, ran Fernox F3 cleaner through twice for a day each, with lots of flushing etc. in between. (trying again now, been in system 5 days)
Drain pipes are hidden underground so can't see what is flushed but rad bleeds are usually clear.
I guess the most likely is I loosened some muck which is blocking somewhere but I can;t think where consdiering how well the system works individually.
Also slight suspicious old grunfos pump (20+ yrs old) not in the best of health, but still working, but whilst all the flushing & draining thought would replace afterwards. New Grundfos 15/60 (replaced 15/50) tried all settings 1-3. Identical position & flow direction.
I would have though unlikely that the=is more powerfull pump could starce the un-pumped primary, setting 1 must be low enough on test - Back On 3 at the moment.
Any idea's.
20 year old Potterton Kingfisher II. (& 20 year Hot water cylinder)
Open Vented system.
Before you say, I am considering new condensing boiler but costly to change (BG wanted £4700) & till now absolutley 100% reliable, have read quite a lot of problems with newer boilers so not so committed.
Sorry very long winded post but hoped the more info the better.
No port valves or tank stat. so HW always ON with CH.
No problem with actually hot water flow from taps, problem is in the primary.
Central Heating works well. 16 rads get hot, some very (balanced & some TVR's) 5 bed house warm.
If I turn CH off, hot water does heat up, albeit quite slow now but will get to 70 degrees. I emptied for 1st time till cold running through & took nearly 3 hours to get to 60+ degrees, so guess this not quite right. However, normally have some v.hot still left in cylinder seemed to recover in 1-2 hours so not really noticed before.
Soon as I turn heating on & pump starts HW does not heat up & might even loose a little temperature. Rads get warm pretty quick.
Primary to cylinder not pumped and goes into loft towards header, branches off before & down to radiator in bathroom (always hot)
This bathroom radiator also fails to heat or retain heat in the same way the HW cylinder does when central heating is engaged.
I assume perhaps some sort of air lock or perhaps is there something in the boiler itself that favours the flow to the CH and starves the primary F&R.
Air Lock, I don't see where this could be, if in cylinder surely it would rise up the coil & eventually out the vent (Vent is above water level & header fills & empties fine) I also assume not in cylinder as pipe above cylinder input (going to vent) cools also. Also when only HW & working would this not push air out. Been like it for week now. Can you get air lock in the bolier itslef?
If I hold the primary flow pipe (When cooled a bit) I can feel what seems a little like bubbling, plop... plop 5 or 6 times in a minute, but not sure if just water movement or pump/bolier vibration.
There is a fitting 12" from boiler on route to cylinder & on, looks like some sort of valve, T piece but just a couple of nuts on the top with 8mm 'ish hole in it, quite furr'd up with limescale
Have empied & filled dozens of times during my 20 years with it & never had any issues refilling, rad's bleed easily & reliably.
Quite a soft water area but kettle will get pretty bad in a few years.
Gas bills have been bad, even before the cold spell, 30-50% up but with price increases and so many estimates its hard to tell. £200 per month, CH on 24/7 @ 19 day & overnight & 20 degrees when occupied.
Now, Have I caused this !!
A few months back I put a new digital room stat. in place of old dial. Great piece of kit, different temps at time of day etc etc.
However, I wonder if it keep heating cyling longer than before, doubt it but hey, trying to cover all bases.
Pre snowy, v cold snap I thought system could do with a clean. Not being very cold before perhaps would not have noticed if it was working as during normal climate, room stat goes off reguarly giving hot water time to recover.
Anyway, ran Fernox F3 cleaner through twice for a day each, with lots of flushing etc. in between. (trying again now, been in system 5 days)
Drain pipes are hidden underground so can't see what is flushed but rad bleeds are usually clear.
I guess the most likely is I loosened some muck which is blocking somewhere but I can;t think where consdiering how well the system works individually.
Also slight suspicious old grunfos pump (20+ yrs old) not in the best of health, but still working, but whilst all the flushing & draining thought would replace afterwards. New Grundfos 15/60 (replaced 15/50) tried all settings 1-3. Identical position & flow direction.
I would have though unlikely that the=is more powerfull pump could starce the un-pumped primary, setting 1 must be low enough on test - Back On 3 at the moment.
Any idea's.
