Combi Heating

[Dagman]

Hi Ab'ers, does anyone know... I've had a new baxi 800 condenser combi heating unit fitted (old one was basic combi), is it important to have one fully open radiator (in my case bathroom) with 'no regulating valves' on? Nothing in the user guide says anything. It's just that the radiator is 50' hot all the time the heating is on, guide says heating should be running at 50'+ and set room temp of 18'+ for efficiency. Any ideas? TIA.

[The Builder]

Modern combis are quite sophisticated now. All sorts of bypass valves/temperature sensors etc.  In the event of boiler overheat, they would probably just shut down on their own. That would protect the boiler, but you'd have no heating at all until it either resets itself of you do it manually.

So... good practice is to include a 'heat sink rad', sometimes known as a 'heat leak rad.' Bathroom is ideal. A towel rail in the system is perfect since it's always needed.

No TRVs. Just standard 'lockshield valves' on the one heat sink rad or towel rail.

[Dagman]

Thanks The Builder, didn't really know if it has an internal bypass. Our old system ran at about 35' with the bathroom rad warm but now seems way too hot at the recommended temp and seems a waste of energy. The rest of the rads are just right but not the bathroom. The thermostat downstairs is at 21' but I don't understand why 50' is in the bathroom. Suppose the next gas bill will show something, either a saving or not. Thanks for the info.