Do I need a radiator upgrade?

dr_bogenbroom

I also meant to add that my boiler doesn’t have a temperature dial, just a dial numbered 0-5 and it’s at 3.5 so not sure what this translates to in temperature?

Albermarle

dr_bogenbroom said:

FreeBear said:

What I usually recommend is measure up the room sizes & window/door areas. Punch the numbers in to this online calculator - https://www.stelrad.com/basic-heat-loss-calculator/ and note the recommended radiator sizes. Play around with the "System Temperature" and compare the numbers at 40°C (flow temp of 60°C) and 30°C (flow temp 50°C).

Measure the size & type of the existing radiators and take a look at https://www.simplifydiy.com/plumbing-and-heating/radiators/power to get an approximate heat output at a flow temperature of 70°C. The two sets of numbers should be fairly close if your heating system had been properly specified at installation time.

If the numbers are close, but rooms are not heating up effectively, it is possible likely that the system needs balancing. In the meantime, increasing the flow temperature will boost the heat output from all the radiators. Try not to go much above 70°C or you will reduce the boiler efficiency by quite a bit.

Side note - 15mm pipes to the radiators is good, but you also need to know what size the main feed & return pipes are. 15mm pipe will carry ~8kW of heat, and 22mm is good for ~18kW (dependent on pump speed and water temperatures).

Hi @FreeBear

I’m just getting round to doing some calculations in my living room as it’s one of the rooms that never seems to get warm.

I calculated the Watts requirement to be 1503 W according to the calculated on:

https://www.bestheating.com/btu-calculator

I used the following information in the calculator and I’ve added in some extra detail:

Room size:

L: 4.95m

W: 4.16m

H: 2.26m

Window size: 5.2m2 (2 x double glazed) - original to the house built in 1994 (so no Argon). I’ve draft proofed with weather strips temporarily.

Concrete floor - not sure if this will have insulation or not?

2 external walls, double skin with insulated  cavity

Chimney (currently blocked with insulation in a bag)

Room upstairs is a large heated master bedroom. Insulation in the attic is about 350mm.

I then worked out using the link you provided that my current radiator outputs 3120 W using the following details:

Radiator size:

L: 1.8m

W: 0.45m

Output: 3120 W

This suggests my radiator is way oversized for the room but this can’t be right? I can hold my hand on to the radiator for about 6s before it gets too sore and I have to let go - but even if it was under performing by 50% it should still be enough? 

I’m thinking I’ve done something wrong or missing something here if someone can help?

Thanks.

Just putting all the technical stuff to one side, it just does seem odd that room feels cold. For example, our living room is a very similar size. Just one outside wall/large double glazed bay window. Open chimney ( occasional use of fake coal gas fire) Suspended wooden floor and carpets.
Traditional double skin radiator is at least 30 years old. Also 1.8M long and  6 cms wide ( presume yours is not really 45 cms wide and it is a typo).
With the heating on and the TRV turned up, it is hottish to touch. Boiler flow temp around 60 ish.
The room keeps nice and warm, and even in this weather I turn the TRV down some of the time.
Couple of points . The room is South facing, but not sure that makes so much difference at this time of year. Perhaps more importantly, there is someone at home most of the time/every evening, so it gets heated every day for a few hours at least.

Albermarle

dr_bogenbroom said:

I also meant to add that my boiler doesn’t have a temperature dial, just a dial numbered 0-5 and it’s at 3.5 so not sure what this translates to in temperature?

Probably around 65.

FreeBear

Raising the temperature by 3°C in just 24 minutes is pretty good.

I have a box room of a similar size with a 500x600mm T21 radiator (rated at ~670W). Get a 1°C per hour temperature increase and a 0.5°C/h drop at -1°C outside. After I had insulated the walls & ceiling in that room, I put a fan heater in there connected to a low hysteresis thermostat and monitored the energy consumption. This suggested that heat loss was in the order of 120Wh when ruddy cold outside.

Your T11 radiator should put out 900W @  ΔT50°C (70°C flow temperature). Ample for the size of room.

dr_bogenbroom

FreeBear said:

Raising the temperature by 3°C in just 24 minutes is pretty good.

I have a box room of a similar size with a 500x600mm T21 radiator (rated at ~670W). Get a 1°C per hour temperature increase and a 0.5°C/h drop at -1°C outside. After I had insulated the walls & ceiling in that room, I put a fan heater in there connected to a low hysteresis thermostat and monitored the energy consumption. This suggested that heat loss was in the order of 120Wh when ruddy cold outside.

Your T11 radiator should put out 900W @  ΔT50°C (70°C flow temperature). Ample for the size of room.

Yeah the heat loss though was pretty rapid - much quicker than yours. I’ll have to start saving the pennies for window upgrades possibly. 

I did the same experiment in the living room I was originally talking about - used a 2000W electric heater and it raised the temp from 15.1 degrees to 17.9 degrees in an hour… seeing what the drop is like now. Outside temp is about 4 degrees.

FreeBear

dr_bogenbroom said: I did the same experiment in the living room I was originally talking about - used a 2000W electric heater and it raised the temp from 15.1 degrees to 17.9 degrees in an hour… seeing what the drop is like now. Outside temp is about 4 degrees.

Is that with the CH on as well, or just the electric heater ?

dr_bogenbroom

That’s just with the electric heater - it’s now been 40 min since I turned it off and were now back down to 16.1 degrees so it does seem to lose heat fast? I could be over thinking it? I’ll be losing heat through the ceiling though to the upstairs bedroom as that isn’t being heated a present. 

On a slightly separate note - if the downstairs is colder than the upstairs is there any benefit to insulating between floors? 

FreeBear

The heat loss to the bedroom above will be minimal. There isn't much to be gained by putting insulation between the joists. I've done it here, but that was only because I had taken down ceilings. Based on data collected, it has made no discernible difference to heat retention or cut down on noise transmission. However, it may have improved fire safety slightly as fibreglass is non-combustible. Not that I want to test that any time.

dr_bogenbroom

FreeBear said:

The heat loss to the bedroom above will be minimal. There isn't much to be gained by putting insulation between the joists. I've done it here, but that was only because I had taken down ceilings. Based on data collected, it has made no discernible difference to heat retention or cut down on noise transmission. However, it may have improved fire safety slightly as fibreglass is non-combustible. Not that I want to test that any time.

Thanks that’ll save me a wasted huge job! It must be the windows then - or it’s just a cold house for some reason. I’ll save the extra and get triple glazed in a few years 

pieroabcd

Do you keep the door open?
Keeping it closed makes a huge difference to preserve heat.