Hi everyone,
This is my first post on here so be gentle.
I've had two heating engineers come in to try and resolve this problem. Both have changed small bits and pieces, but neither have seemed to resolve the problem.
I have recently moved into a new house, it had a very old floorstanding boiler which has been replaced with a Glowworm Ultracom hxi 38kw boiler. The boiler sits downstairs, there is a pump, cylinder and expansion vessel upstairs.
Ignoring the hot water, there are two circuits for the heating, each with their own zone valve. One circuit does the radiators upstairs, and one or two radiators downstairs, and the second circuit does the underfloor heating which is a system by Warmafloor. (There is a three zone heating controller so the HW/underfloor/CH can be controlled independently.)
The underfloor heating flow goes downstairs to a cupboard where you have a thermostatic valve (that's currently set as open as possible), and then a pump, and then water goes info a manifold. The underfloor has 5 different thermostats that turn solenoids on/off for the different areas.
We first noticed the problem after the new boiler had been installed. Basically the boiler would fire up for a few minutes and then throttle right back. I went through the diagnostic menu of the boiler to find the error code, and it gave an error code of 53 - which means the difference in temperature between flow and return was too high. I looked into it further and the manual for the boiler says the temperature difference should be no more than 20c.
The set point for the boiler is currently 80c.
When the boiler is warming up a cold system, the difference between flow and return will hover at 25-30c. However, it seems to be that when it exceeds 30c for about 10 seconds, it will cut out and go into "limp" mode - where it is just burning a trickle of gas and not really doing any sufficient heating.
The central heating pump upstairs is quite a big one, it's set on its highest output which is 0.5 amps/120 watts. (I don't know what this means in litres/minute.)
The secondary issue that I have is that when the water in the system is already at 60c and the boiler is off, when the boiler switches on it seems to burn gas at maximum attack for a period of time before modulating to achieve the target temperature of 80c. The problem with this is that because on maximum attack it will raise the water 25-30c, it quickly exceeds the 80c set point and then cuts off gas entirely, I assume for safety reasons, for about 5 minutes.
The most recent plumber that came in said the lack of flow was caused either by air trapped in the system or cold-water stop cocks on the flow and return. He put in thumb valves to release the air, and also removed the stop cocks. Before this happened, we'd occasionally hear a sound like someone drilling into a masonry wall coming from the heating cupboard upstairs - I think this may have been the pump cavitating. Would this be likely to cause permanent damage to the pump? Is there a way I can test the output of the pump?
The other thing I've noticed is that with the way the underfloor heating works, it will use solenoids to release hot water into the pipes that run underneath the floor - the net effect of this thought is that a "slug" of cold water comes out of the floor and into the system, quickly dropping the return temperature of water to the boiler.
I'd really appreciate input on what I should look at or how I can diagnose what to do next.
This is my first post on here so be gentle.
I've had two heating engineers come in to try and resolve this problem. Both have changed small bits and pieces, but neither have seemed to resolve the problem.
I have recently moved into a new house, it had a very old floorstanding boiler which has been replaced with a Glowworm Ultracom hxi 38kw boiler. The boiler sits downstairs, there is a pump, cylinder and expansion vessel upstairs.
Ignoring the hot water, there are two circuits for the heating, each with their own zone valve. One circuit does the radiators upstairs, and one or two radiators downstairs, and the second circuit does the underfloor heating which is a system by Warmafloor. (There is a three zone heating controller so the HW/underfloor/CH can be controlled independently.)
The underfloor heating flow goes downstairs to a cupboard where you have a thermostatic valve (that's currently set as open as possible), and then a pump, and then water goes info a manifold. The underfloor has 5 different thermostats that turn solenoids on/off for the different areas.
We first noticed the problem after the new boiler had been installed. Basically the boiler would fire up for a few minutes and then throttle right back. I went through the diagnostic menu of the boiler to find the error code, and it gave an error code of 53 - which means the difference in temperature between flow and return was too high. I looked into it further and the manual for the boiler says the temperature difference should be no more than 20c.
The set point for the boiler is currently 80c.
When the boiler is warming up a cold system, the difference between flow and return will hover at 25-30c. However, it seems to be that when it exceeds 30c for about 10 seconds, it will cut out and go into "limp" mode - where it is just burning a trickle of gas and not really doing any sufficient heating.
The central heating pump upstairs is quite a big one, it's set on its highest output which is 0.5 amps/120 watts. (I don't know what this means in litres/minute.)
The secondary issue that I have is that when the water in the system is already at 60c and the boiler is off, when the boiler switches on it seems to burn gas at maximum attack for a period of time before modulating to achieve the target temperature of 80c. The problem with this is that because on maximum attack it will raise the water 25-30c, it quickly exceeds the 80c set point and then cuts off gas entirely, I assume for safety reasons, for about 5 minutes.
The most recent plumber that came in said the lack of flow was caused either by air trapped in the system or cold-water stop cocks on the flow and return. He put in thumb valves to release the air, and also removed the stop cocks. Before this happened, we'd occasionally hear a sound like someone drilling into a masonry wall coming from the heating cupboard upstairs - I think this may have been the pump cavitating. Would this be likely to cause permanent damage to the pump? Is there a way I can test the output of the pump?
The other thing I've noticed is that with the way the underfloor heating works, it will use solenoids to release hot water into the pipes that run underneath the floor - the net effect of this thought is that a "slug" of cold water comes out of the floor and into the system, quickly dropping the return temperature of water to the boiler.
I'd really appreciate input on what I should look at or how I can diagnose what to do next.
