Setting thermostatic radiator valves

matt_drummer

quartzz said:

information to read through. I think it's going to be a try-it-and-see thing. I suspect until yesterday the boiler was set hotter than it needed to be because the previous owners just wanted "hot", and weren't concerned about the bills

Matt - all 3 need to be monitored? (boiler heating element elec, boiler motor/pump elec, and oil) I've been checking my ultra sonic receiver gadget every few days. happily the LCD level meter hasn't budged since I've been here. which either means I'm not using a lot of oil, or it's broken

You do realise that all of your heat comes from burning oil don't you?

The electricity consumption is minor in comparison!

quartzz

if I'm honest I didn't think about it too much, I thought "heating element" "pump" "oil". but yes if the heat is from the oil producing a flame, then......yes, that. I'd be interested in information about why heating the water to a lower temperature doesn't use less oil -- which again without thinking about it, I would have thought would be the case

doodling

Hi,

FreeBear said:

quartzz said: Matt - all 3 need to be monitored? (boiler heating element elec, boiler motor/pump elec, and oil) I've been checking my ultra sonic receiver gadget every few days. happily the LCD level meter hasn't budged since I've been here. which either means I'm not using a lot of oil, or it's broken

There is no heating element inside the KC90HEE combi boiler. Just a fan, pump, and some simple electronics. Looking at the specifications, electricity consumption is a constant 200W regardless of heating load.

Depending on exactly which model you have, oil consumption is steady at 2.35-2.98l per hour. Changing the flow temperature or TRV settings is not going to have any discernible affect on energy consumption - A lower flow temperature will improve fuel efficiency slightly though.

In general, providing you don't try to achieve significant temperature differences between rooms, them turning down TRVs will reduce oil consumption as the boiler will fire for a smaller proportion of the time.  Fundamentally, a colder house generally implies that you are using less oil.

Problems arise if you try to achieve large temperature differentials between rooms as the radiators in the rooms set to the higher temperatures have to work harder which potentially reduces efficiency which works against you but this is a second order effect and is probably not relevant to the OP's case.

doodling

Hi,

quartzz said:

if I'm honest I didn't think about it too much, I thought "heating element" "pump" "oil". but yes if the heat is from the oil producing a flame, then......yes, that. I'd be interested in information about why heating the water to a lower temperature doesn't use less oil -- which again without thinking about it, I would have thought would be the case

At a simple level, providing the rooms reach the same temperature then reducing the temperature of the water coming from the boiler doesn't reduce oil consumption.  What happens is that your TRVs will open slightly to allow more water through the radiators so whilst your boiler might be heating to a lower temperature, it is heating more of it.

At a less simple level, boilers are more efficient if the water flowing through them is colder so yes, you will save money by reducing the temperature of the water flowing through the boiler.  How low you can set this temperature is determined by the size of your radiators (and by your hot water heating arrangements).

FreeBear

doodling said:

Hi,

FreeBear said:

quartzz said: Matt - all 3 need to be monitored? (boiler heating element elec, boiler motor/pump elec, and oil) I've been checking my ultra sonic receiver gadget every few days. happily the LCD level meter hasn't budged since I've been here. which either means I'm not using a lot of oil, or it's broken

There is no heating element inside the KC90HEE combi boiler. Just a fan, pump, and some simple electronics. Looking at the specifications, electricity consumption is a constant 200W regardless of heating load.

Depending on exactly which model you have, oil consumption is steady at 2.35-2.98l per hour. Changing the flow temperature or TRV settings is not going to have any discernible affect on energy consumption - A lower flow temperature will improve fuel efficiency slightly though.

In general, providing you don't try to achieve significant temperature differences between rooms, them turning down TRVs will reduce oil consumption as the boiler will fire for a smaller proportion of the time.  Fundamentally, a colder house generally implies that you are using less oil.

I should have added "whilst the boiler (burner) is running".

quartzz

doodling said:

Problems arise if you try to achieve large temperature differentials between rooms as the radiators in the rooms set to the higher temperatures have to work harder which potentially reduces efficiency which works against you but this is a second order effect and is probably not relevant to the OP's case.

right, I need to say, this is the case. in the rooms I have here, the two downstairs are heated to a habitable temperature, but the rooms upstairs are basically "off" (with the exception of the bathroom, which has a towel rail heater which doesn't use a TRV, just has two "hard wired" knobs)

just to add, yes I do occasionally turn the upstairs TRV's to 5, to get some hot water circulating

quartzz

right, I have to say at 4pm I finally had enough. boiler temperature dial direction wise, not time. the water wasn't hot enough to get the room temperature, so the system never stopped making a noise. it started driving me nuts. it was like being in a permanent rainstorm. I've changed it to 5pm and before the downstairs was noticeably cooler just for today, but now it's normal temperature. 21.5 according to the thermometer. the TRV's downstairs are sitting at about 4.3

there actually is an additional issue but I'll have to live with it. my hot water pressure from the tap seems to be higher than the cold water pressure. this means that for the shower, using the hot tap as much as possible is preferred, because of the higher shower head rate. so the more cold water (because the hot is too hot to use for the shower on its own), the less shower pressure I get. that was also one of the main reasons for wanting the hot water more useable, but it's balancing between radiators and hot water (the boiler only has a single temp control for water and heating). very first world problems. better than living 65 million years ago and getting eaten by a T-Rex.

FreeBear

quartzz said:

right, I have to say at 4pm I finally had enough. boiler temperature dial direction wise, not time. the water wasn't hot enough to get the room temperature, so the system never stopped making a noise. it started driving me nuts. it was like being in a permanent rainstorm. I've changed it to 5pm and before the downstairs was noticeably cooler just for today, but now it's normal temperature. 21.5 according to the thermometer.

Doing a little bit of digging - The control on the boiler should set the flow temperature between 50°C and 80°C. With that little tidbit, you should be able to estimate what you've set your boiler to run at. A couple of cheap thermometer modules clipped to the main flow & return pipes will confirm what temperature you've set the dial to.

If the flow temperature is set too low, the boiler is likely to short cycle (pulsing on & off) which is bad for efficiency and long term reliability. Ideally, you want 10-15 minutes of off time between burn cycles.