I have an existing customer with a room in which the existing radiator is of sufficient output, but there are French doors and it really needs some heat on each side of them to avoid a cold area on one side. We have established (by experiment with a small oil-filled radiator) that adding even a 500W radiator in that corner would make the customer comfortable, and the easiest way would be to tee off the existing flow and returns. The trouble is that the velocity of the flow and returns is already close to 1.5m/s (if the system is balanced to DT11 across emitters) so I cannot add anything to them, things being as they are.
It has occurred to me, however, that the boiler is a modern condensing combi (Baxi) and would happily run at DT20 which would of course almost halve the flow rate. Although using DT20 in that room would reduce the heat output of the existing radiator, I would be adding a radiator to that room so all would be well provided I size everything right. If I went ahead and did this but left the rest of the house at DT11 across emitters, would I be asking for trouble, or is this something that the boiler would usually be designed to handle (logically, TRVs mean that boilers deal with this sort of situation all the time anyway). Ultimately, if this were my own house I would be considering resizing all the radiators to run at 50/30 and rebalancing the entire system, but you can't quote for a new heating system when the budget is only for one new radiator. It just seems a bit of a waste of money to run new flows and returns to allow that room to run at DT11 if, in the long-term, it seems heating systems are all going to end up as low-temperature DT20 systems, and if the existing boiler would be happy running some rooms at DT11 and others at DT20.
What are people's thoughts on this? Many thanks for any ideas...
It has occurred to me, however, that the boiler is a modern condensing combi (Baxi) and would happily run at DT20 which would of course almost halve the flow rate. Although using DT20 in that room would reduce the heat output of the existing radiator, I would be adding a radiator to that room so all would be well provided I size everything right. If I went ahead and did this but left the rest of the house at DT11 across emitters, would I be asking for trouble, or is this something that the boiler would usually be designed to handle (logically, TRVs mean that boilers deal with this sort of situation all the time anyway). Ultimately, if this were my own house I would be considering resizing all the radiators to run at 50/30 and rebalancing the entire system, but you can't quote for a new heating system when the budget is only for one new radiator. It just seems a bit of a waste of money to run new flows and returns to allow that room to run at DT11 if, in the long-term, it seems heating systems are all going to end up as low-temperature DT20 systems, and if the existing boiler would be happy running some rooms at DT11 and others at DT20.
What are people's thoughts on this? Many thanks for any ideas...
