4 bed house with traditional open-vented system.
The old cast-iron core boiler was inefficient and the core was weeping but we used to have lashings of very hot water though the cylinder was small, only about 100 litres.
About 3 years ago we replaced the boiler with a Glow worm Flexicom 24hx running through a Honeywell Y plan valve. The major pipework to the rads is 22mm but to the cylinder is 15mm. The new 160 litre cylinder is a modern half-hour job with two coils; the upper for the HW circuit and the lower is finned for solar. Since I'm pre-heating the water by running my solar panel through a second 160 litre cylinder in tandem with the main house cylinder the lower finned coil isn't in use except as a dump for excess solar water on the rare occasions when my solar system achieves 60 c.
Since fitting the new boiler and cylinder the hot water has been consistently inadequate. This morning the HW was timed ON for 2 hours 30 so the cylinder should have been full of water at 60c. I went out on the bike, came back and had disappointingly tepid shower, then I turned on the HW and watched the temperature display on the front of the boiler: it started at 54 degrees, the burner fired at a low rate, the temperature climbed within about 2 minutes to 82 degrees and the burner cut out. This tells me the coil isn't extracting enough heat from the HW circuit. We have had the boiler checked by a Glow worm engineer and he thought the coil might have a blockage and the symptoms I describe above would seem to support this. For a week or two after the new cylinder was first fitted I could hear water trickling within the cylinder when the HW was running. I have recently fitted a new Y plan valve (original was clunking on changeover) and I'm sure the HW circuit is clear of air; the flow is quiet and there's an auto-bleed float thingy on a T right above where the HW circuit enters the coil.
The cylinder stat is set to 60c and is at roughly the same height as the bottom exit of the upper, main coil.
Could we re-jig the HW circuit so it runs thrugh both the regular coil AND the lower finned solar coil?
What tests can anybody suggest for a blocked coil?
My plumber is serious grown-up bloke, he has been back a couple of times and he thinks the HW is adequate and can't think of any reason why it should under-perform. Perhaps we are expecting too much from a modern condensing boiler?
Any thoughts?
The old cast-iron core boiler was inefficient and the core was weeping but we used to have lashings of very hot water though the cylinder was small, only about 100 litres.
About 3 years ago we replaced the boiler with a Glow worm Flexicom 24hx running through a Honeywell Y plan valve. The major pipework to the rads is 22mm but to the cylinder is 15mm. The new 160 litre cylinder is a modern half-hour job with two coils; the upper for the HW circuit and the lower is finned for solar. Since I'm pre-heating the water by running my solar panel through a second 160 litre cylinder in tandem with the main house cylinder the lower finned coil isn't in use except as a dump for excess solar water on the rare occasions when my solar system achieves 60 c.
Since fitting the new boiler and cylinder the hot water has been consistently inadequate. This morning the HW was timed ON for 2 hours 30 so the cylinder should have been full of water at 60c. I went out on the bike, came back and had disappointingly tepid shower, then I turned on the HW and watched the temperature display on the front of the boiler: it started at 54 degrees, the burner fired at a low rate, the temperature climbed within about 2 minutes to 82 degrees and the burner cut out. This tells me the coil isn't extracting enough heat from the HW circuit. We have had the boiler checked by a Glow worm engineer and he thought the coil might have a blockage and the symptoms I describe above would seem to support this. For a week or two after the new cylinder was first fitted I could hear water trickling within the cylinder when the HW was running. I have recently fitted a new Y plan valve (original was clunking on changeover) and I'm sure the HW circuit is clear of air; the flow is quiet and there's an auto-bleed float thingy on a T right above where the HW circuit enters the coil.
The cylinder stat is set to 60c and is at roughly the same height as the bottom exit of the upper, main coil.
Could we re-jig the HW circuit so it runs thrugh both the regular coil AND the lower finned solar coil?
What tests can anybody suggest for a blocked coil?
My plumber is serious grown-up bloke, he has been back a couple of times and he thinks the HW is adequate and can't think of any reason why it should under-perform. Perhaps we are expecting too much from a modern condensing boiler?
Any thoughts?