B
borisblank
Hi,
Newbie non-plumber after advice, so please be gentle.
I've recently had my single garage converted and the central heating extended to a new radiator. The conversion is fully insulated, compliant to building regs, and heat retention seems to be about on par with the house, if not a touch better. However, the temperature in the room is always a fair bit colder than in the house, e.g. 15 degrees in the room vs 20 in the house.
The setup:
- Radiator is 7000 BTU or thereabouts, with a thermostatic valve. [EDIT: it looks like it's closer to 5000 BTU/h] For testing I've removed the thermostatic head, so we can rule that out.
- The flow return have been routed in 10mm microbore teed from the 10mm tails in the kitchen. There is apparently 15mm in the wall (stud wall, so could be opened up) and the runs before the tees are reasonably short. Distance the new pipework covers is maybe 3-4 meters, with several right angles in the run. The pipes run through a shared wall and do not go outside.
- There is no door through from the house, so the room is completely isolated and won't get residual heat from the main part of the system.
- The house radiators are all balanced, with flow/return temperature differences at the boiler spec of 11 degrees. The new radiator has both valves wide open at the moment. Temperature differences there seem to be fairly chaotic, measuring anywhere between 8 and 20 degrees.
- The pump has been turned up to full to try and force more water through the new pipework. It's annoyingly noisy now if I'm honest.
The temperature of the conversion lags the house by some margin. It seems to catch up if the system indoors stays on for longer before the thermostat kicks in and this has the effect of raising the temperature in the conversion when it's colder outside. For instance, when it's 10 degrees outside and 20 degrees in the house, it's 15 degrees in the conversion. When it's 8 degrees outside it's 16 degrees in the conversion.
If the thermostat is wound right up, the new radiator seems to get hot at pretty much the same rate as those in the house and gets just as hot. It feels to me like there could be a delay when the system is pushing out moderately warm water which reduces as it gets up to temperature. The main system only comes on for about 4 minutes per hour when it's 10 degrees outside and the radiators then only get warm and will cool more-or-less to ambient between cycles.
We've discussed with the plumber who originally did the work and he's suggested a couple of approaches.
1. Replace the 10mm run to the conversion with 15mm and take it all the way back to the 15mm flow/return in the kitchen. This ought to double the amount of water and heat to the new rad and help boost the response, even when the flow temps are quite low. Since the conversion is now finished and some of the pipework is sealed behind a wall, another option to avoid too much disruption was to upgrade to 15mm except where passing through the wall and still tee off at the 10mm kitchen tails. It seems to me that leaving any of the 10mm is going to restrict flow, regardless of length.
2. Route from a bedroom upstairs, running 15mm from what is hopefully a 25mm flow/return. This would be under the floor as a wall run would be too disruptive. With this approach joists would have to be notched to run the pipe around and the run would have to pass through the loft space of the garage conversion.
The second seems more likely to be a guaranteed solution, albeit with plenty of scope for unexpected problems. Is the idea of replacing most of the 10mm for the first option worth doing as a sanity to check, replacing the lot if it gives a moderate improvement?
..or is there another answer?
Cheers,
Boris the B
Newbie non-plumber after advice, so please be gentle.
I've recently had my single garage converted and the central heating extended to a new radiator. The conversion is fully insulated, compliant to building regs, and heat retention seems to be about on par with the house, if not a touch better. However, the temperature in the room is always a fair bit colder than in the house, e.g. 15 degrees in the room vs 20 in the house.
The setup:
- Radiator is 7000 BTU or thereabouts, with a thermostatic valve. [EDIT: it looks like it's closer to 5000 BTU/h] For testing I've removed the thermostatic head, so we can rule that out.
- The flow return have been routed in 10mm microbore teed from the 10mm tails in the kitchen. There is apparently 15mm in the wall (stud wall, so could be opened up) and the runs before the tees are reasonably short. Distance the new pipework covers is maybe 3-4 meters, with several right angles in the run. The pipes run through a shared wall and do not go outside.
- There is no door through from the house, so the room is completely isolated and won't get residual heat from the main part of the system.
- The house radiators are all balanced, with flow/return temperature differences at the boiler spec of 11 degrees. The new radiator has both valves wide open at the moment. Temperature differences there seem to be fairly chaotic, measuring anywhere between 8 and 20 degrees.
- The pump has been turned up to full to try and force more water through the new pipework. It's annoyingly noisy now if I'm honest.
The temperature of the conversion lags the house by some margin. It seems to catch up if the system indoors stays on for longer before the thermostat kicks in and this has the effect of raising the temperature in the conversion when it's colder outside. For instance, when it's 10 degrees outside and 20 degrees in the house, it's 15 degrees in the conversion. When it's 8 degrees outside it's 16 degrees in the conversion.
If the thermostat is wound right up, the new radiator seems to get hot at pretty much the same rate as those in the house and gets just as hot. It feels to me like there could be a delay when the system is pushing out moderately warm water which reduces as it gets up to temperature. The main system only comes on for about 4 minutes per hour when it's 10 degrees outside and the radiators then only get warm and will cool more-or-less to ambient between cycles.
We've discussed with the plumber who originally did the work and he's suggested a couple of approaches.
1. Replace the 10mm run to the conversion with 15mm and take it all the way back to the 15mm flow/return in the kitchen. This ought to double the amount of water and heat to the new rad and help boost the response, even when the flow temps are quite low. Since the conversion is now finished and some of the pipework is sealed behind a wall, another option to avoid too much disruption was to upgrade to 15mm except where passing through the wall and still tee off at the 10mm kitchen tails. It seems to me that leaving any of the 10mm is going to restrict flow, regardless of length.
2. Route from a bedroom upstairs, running 15mm from what is hopefully a 25mm flow/return. This would be under the floor as a wall run would be too disruptive. With this approach joists would have to be notched to run the pipe around and the run would have to pass through the loft space of the garage conversion.
The second seems more likely to be a guaranteed solution, albeit with plenty of scope for unexpected problems. Is the idea of replacing most of the 10mm for the first option worth doing as a sanity to check, replacing the lot if it gives a moderate improvement?
..or is there another answer?
Cheers,
Boris the B
Last edited by a moderator:
Room size is about 2.5 x 7.8 x 2.4 m and wants a 3888 BTU rad according to B&Q's calculator.