rads not going above 60

[chatlow]

Tried setting 5 but same story, rads didn't go above 55 at best. I suspect the issue might be partly because we are running both HW and CH at same time throughout the day. Not giving the boiler enough time to heat up the thermal store before the pumps pass to the rads. Especially first thing in the morning when it's cooled overnight. My theory anyway.

Perhaps only having the HW on for an hour first then turning CH would be better.

 

[Ivor Windybottom]

Have you looked at the water? You should be able to check it by squirting into some kitchen roll when bleeding. It may benefit from a water change, perhaps with a rinse. Often the water's as old as the boiler, your rads may be full of sludge.

It may be that your rads are just inadequately small, in which case a new boiler isn't going to help. You could use one of the many radiator calculators available onlline, as though you're installing a new system. Design for a temperature of 60, see if what you end up with are bigger than what you already have. People often cheap out on radiators when fitting, as bigger costs more.

If replacing rads then check current best practice. The idea now is to fit rads that would be adequate if/when the gas boiler gets swapped for a heat pump in future. Think they use a design temp of 50. Bigger won't do any harm, will just cost a bit more.

If you're thinking of a new boiler then may be worth considering a heat pump now, you'll get £7500 paid by the government, you could end up paying next to nothing. Despite internet theories, they do work well and cost about the same as or less than gas. Gas prices may rise in future relative to electricity.

 

[chatlow]

yes i bled all rads (no air). water isn't clear but ran freely. I currently have just the water on at the moment for an hour to heat up the store, will then put CH on and see if that has helped

 

[Ivor Windybottom]

I still don't understand your issue, it sounds like you're complaining about it all working as expected. The radiators will always be a lower temperature than the outlet from the boiler, as their whole purpose is to lose heat, into the room. Water goes out of the boiler hot, the radiators let the heat out into the room, it goes back to the boiler at a lower temperature then goes back to the boiler to be heated again.

Your hot water is in an insulated cylinder, so it will heat to near enough the flow temperature.

If you lagged your radiator as well as the HW cylinder then you might get it near enough to the flow temperature. But then it wouldn't be heating the room!

 

[chatlow]

I still don't understand your issue, it sounds like you're complaining about it all working as expected. The radiators will always be a lower temperature than the outlet from the boiler, as their whole purpose is to lose heat, into the room. Water goes out of the boiler hot, the radiators let the heat out into the room, it goes back to the boiler at a lower temperature then goes back to the boiler to be heated again.

Your hot water is in an insulated cylinder, so it will heat to near enough the flow temperature.

If you lagged your radiator as well as the HW cylinder then you might get it near enough to the flow temperature. But then it wouldn't be heating the room!

No, we have a thermal store. This gets heated up when the HW is on. When we want CH, water passes through the store and gets heated there then goes to radiators, so I'm told.

I am not saying the system doesn't work as expected, it does, I'm just wondering how to increase the temperature when CH is on as it's a bit too low currently.... increasing the boiler stat to 5 didn't seem to do much

 

[Rodders53]

How are you measuring the circulating water temperature at the radiators?

IR non contact thermometer?
Thermocouple?
Pipe clamp thermometer?

You are aware of the danger of burns from brief contact with radiators having surface temperatures of 70C and higher I trust. Lower temperatures are safer for the young and elderly.

 

[chatlow]

How are you measuring the circulating water temperature at the radiators?

IR non contact thermometer?
Thermocouple?
Pipe clamp thermometer?

You are aware of the danger of burns from brief contact with radiators having surface temperatures of 70C and higher I trust. Lower temperatures are safer for the young and elderly.

Ir thermometer
Yeah we don't want it piping hot just more than 50-55 (avg is usually 60-70)

 

[BlueLoo]

Ir thermometer
Yeah we don't want it piping hot just more than 50-55 (avg is usually 60-70)

They don't work on white radiators.......

 

[chatlow]

They don't work on white radiators.......

Seems pretty consistent. You can feel the difference between 50 and 60 so don't really need the thermometer

 

[BlueLoo]

Seems pretty consistent. You can feel the difference between 50 and 60 so don't really need the thermometer

They can be inaccurate.
Better to use a contact thermometer on the inlet/outlet pipe

 

[chatlow]

They can be inaccurate.
Better to use a contact thermometer on the inlet/outlet pipe

Thanks it's been fine for this testing as I just need an approx value

 

[chatlow]

gave the thermostat a good clean, set temp on boiler to around 5 and made sure the water was hot (only needed 10 mins) - temp has now increased in the rads to just over 60.
Think it was the mechanical thermostat in hall way that knocks the pump off and it needs replacing. It clicks but is quite a bit off, so will replace

 

[BlueLoo]

Single mechanical thermostats need to be banned.
1940's tech.