Even when you turn up the TRV on the radiator it still takes a while for the hot water to fill the radiator. OK, you can feel the warm water coming into the radiator but the radiator getting hot straight away is unrealistic.Thanks for your reply.
Sorry, I wasn't very clear. I meant when I turn up an individual radiator, I like it to get hot straight away. Sometimes, it doesn't even start to get hot until a while. I didn't mean the temperature of the room.
Thanks for the video recommendation, that should really help.
I thought those were just issues that customers experienced with their particular product. If it's with all of them, I think I might just go for the item linked to above.
Thanks.
As to why modern thermostat, cuts out a little below the setpoint. It's all due to thermodynamics. When the boiler stops, the pump continues circulating for a few minutes and the radiators continue to warm up. That heat then needs to get into the room. The thermostat then senses the actual temp and nudges the boiler a bit to achieve your desired temperature. If the boiler actually stopped at the setpoint, the room temp would rise above that by a degree or two. That occurred in the past with mechanical thermostats and you would experience a cold-warm-cold-warm cycle as the temp would rise abovce your setpoint and then fall below. It's called hysteresis.
You should also find the T4 is less expensive at plumbnation
Honeywell T4 7 Day Programmable Thermostat
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www.plumbnation.co.uk