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Like most of us I followed the energy saving tips and turned down the flow rate on my Worcester Bosch boiler. It was set at around 78c I turned it down to 54c. After a month or so of use I’ve found the downside, it takes a lot longer to heat the rooms up. My heating usually comes on around 5pm and is set to 20.5c, it’s struggling to get above 19.5c by the time it goes off at 10pm.
I’m faced with 2 choices, either turn the flow rate up or increase the daytime (off) temperature from 15c to 18c so the boiler has less work to do when it comes on.
Has anyone else noticed this after reducing flow rate?
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Jojoe, I think you may be misunderstanding what’s going on. When you reduce the temperature on the boiler, it just shuts off the burner earlier to keep the water output at whatever temperature you set it. Nothing to do with the flow rate which is controlled by the pump setting. Lower temperature in the rads will give less heat to the room as you’ve found. As the weather gets colder, the water in the rads will need to be hotter. For now, I would knock the temp up to 60. If that doesn’t heat you room enough, increase it some more.
The effect on gas consumption by reducing boiler temperature isn’t really that much in practice but I do it and prefer rads not to scalding hot when they don’t need to be!
Hi Wigwam, cheers, I’ve upped it to 60 and also increased the daytime temperature a little to 17c. Lots of people on TV were saying adjusting the flow rate has no impact on room temperature, even though my thermostat was set at 20.5c, it just would not reach that.
Like most of us I followed the energy saving tips and turned down the flow rate on my Worcester Bosch boiler. It was set at around 78c I turned it down to 54c. After a month or so of use I’ve found the downside, it takes a lot longer to heat the rooms up. My heating usually comes on around 5pm and is set to 20.5c, it’s struggling to get above 19.5c by the time it goes off at 10pm. I’m faced with 2 choices, either turn the flow rate up or increase the daytime (off) temperature from 15c to 18c so the boiler has less work to do when it comes on. Has anyone else noticed this after reducing flow rate?
Silly question your heating system may be sludge up need the system flushing out, I am assuming you have bled the system at the start of the winter season?
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.
Silly question your heating system may be sludge up need the system flushing out, I am assuming you have bled the system at the start of the winter season?
Yep, it’s thirst thing I did when the rads weren’t getting hot.
Unless it’s a newly installed system, to run a boiler at low temperatures needs bigger radiators (and pipes). And possibly even a bigger boiler!
I have a 18-20 year old Baxi, flow and return pipes are 22mm from the boiler to the front and rear of the house where manifolds reduce piing to 10mm to each rad. Each rad has the correct BTU @delta T50 for the size of the room. The piping and rads were installed by myself when we replaced the back boiler after moving in. With the boiler temp set at 58 it heats the house fine. Oversizing rads for a room running a system or combi boiler is not really a common thing to do and only really seen in the new fangdangled ground/air sourc heatpumps that are designed to run at ultra low temps.
@Jojoe If the system has no air in it, try turning the pump speed down a notch so water circulates slower and/or make sure your radiators are balanced correctly.It would be helpful to know what system you have 🙂
Kezo, I’d love the opportunity to design and install a new system. I put 2 in many years ago. As far as I recall Delta T 50 calls for a flow temp of 75 Deg. You must have much better insulation than this 95 year old house can be made to have. It’s heating was always inadequate, pipes and radiators both too small. I’ve replaced most of the rads but can’t do anything about the pipework…
There’s a risk of introducing a red herring here Oscarmax. Unless the heating system is newish and designed around a low temperature boiler, the radiator sizing would have been designed for a boiler flow temperature of 82 Deg. What Jojoe is experiencing with a low boiler flow temperature is expected and normal. As the weather deteriorates he will need to keep edging the boiler temperature up to keep his room warm. Unless it’s a newly installed system, to run a boiler at low temperatures needs bigger radiators (and pipes). And possibly even a bigger boiler!
Where is the red herring?
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.
Kezo, I’d love the opportunity to design and install a new system. I put 2 in many years ago. As far as I recall Delta T 50 calls for a flow temp of 75 Deg. You must have much better insulation than this 95 year old house can be made to have. It’s heating was always inadequate, pipes and radiators both too small. I’ve replaced most of the rads but can’t do anything about the pipework…
The reason I mentioned Delta was its importance to when your system was designed/fitted. Prior to 2013 the UK was T60, after that it came in line with the rest of the Europe which used T50. So a Delta T60 radiator with an output of 5000BTU would equate to 3945BTU at Delta 50 (BTU at T60x0.789=T50). Most installers or radiator stores compensate fo this depending on the type of home. Heatpump sytems use a much lower Delta raing of arund T30.
If you have a flow temperature from your boiler of 80c in theory the water inside your radiator would be 70c with an average room temp of 20c. 70-20=delta T50 radiator as a guide. The important bit to remember a 80/60 (flow and return) is way way to high for a A/B rated boiler to condensate and be effiecient “A” rated. Most modern boilers condensate at 55-60c (you can check this in your boiler manual) So a modern A rated boiler will quite happily run on T50 radiators at 60c and heat your home to temperatures of up to 25c. At a flow of 60c my radiators are still really too hot to touch if I left my hand on them, but they may take a couple of mins longer to get hot.
As said in my last comment it is important to know the system Joejo has. It equally important that you radiators are balanced correctly.
The boiler is a 4 year old Worcester Bosch installed by British Gas, we have 8 rads 3 newish and 5 quite old (20 years).
The boiler is a 4 year old Worcester Bosch installed by British Gas, we have 8 rads 3 newish and 5 quite old (20 years).
So I take it is a Combi or sytem boiler in which case there should be no issues. Do you know the whether its a 24kw or 30kw. I take it BG power flushed the system and balanced all the rads after fitting it?
Have you bled the radiators?
Do you have Thermostic radiator valves?
It’s a combi 29kw. System was flushed and presume balanced. We have TRV’s on all rads except hallway where the hive thermostat is. All the radiators have been bled. It’s improved since I turned the flow rate up to 60c.
Our combi boiler is set to 60 c seems to be the optimum setting for us.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.
If you pull the bottom cover down, remove the 2 screws and pull it down you will see the pump. There is a switch on the black part where the cable goes in and it likely set to 3 high. Switch it down to 2 and see if that helps.
You could also turn the flow upt to 65c if its easier
Oscarmax, I was concerned you were introducing the prospect of Jojoe thinking his system was faulty when it seemed to me it was behaving perfectly normally.
Oscarmax, I was concerned you were introducing the prospect of Jojoe thinking his system was faulty when it seemed to me it was behaving perfectly normally.
How strange do you think I am sort of idiot?
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.
Oscarmax, I don’t see anything in jojoe’s posts that would cause you to say:
“Silly question your heating system may be sludge up need the system flushing out, I am assuming you have bled the system at the start of the winter season”
As I said, from what he said, his heating is operating normally and simply behaving as expected to the water temperature being turned down. That’s all.
Turning a modern boiler downd to 60c will have no adverse effect on heating your home and a boiler will be at it most efficient. It will condense as the name suggests condensing boiler and be stated in the boiler manual. for my baxi it is 60-65. The link below is for Vaillant, but proves what use to be 80 flow/60 return rule is out of the window with a modern boiler.
My house is a 4 bed dormer style buit in 1963. Other than loft and cavity wall insulation the dormer insulation remains how it was built. With my boiler set temp at 60c it heats the home easily up to 25c if I wished.
Kezo. That is your experience and I’m glad that’s what you’ve found. A condensing boiler will indeed be more efficient run at lower temperatures. but a heating system designed for an 80 Deg flow temp cannot possibly provide the same heat when run at 60 Deg. That’s simple physics.
Yes it can but will take a little longer to heat up the room. If you hold a piece of copper pipe and pour boiling water over it the pipe will become hot and you will burn your hand a bit quicker than if you poured 80c onto a pipe and so on. I got A level physics many years ago in school lol. Its like putting the blower on in your car when the engine is not up to temperature, it will still heat the car at the temp set but take a little longer. Ultimately the aim is to be omfortable in your own home and if the flow temp needs upping there is no reason why you shouldn’t, but by doing so will decrease the efficiency of a A rated boiler to 75-80% which kind of defeats the object.
If you rads are balanced correctly there is no reason lowering the flow temp won’t heat your home. If they aren’t balanced correctly water will either gush through causing the rads to not heat up temp or cause some radiators to be cooler than others. The same applies to pump speed.
Kezo, with respect you are wrong. A radiator giving out 5000 BTU at Delta T 60 will give out less than 4000 BTU at Delta T 50 and over 6000 BTU at Delta T 70. Ignoring balancing and flow rate for now, the size of the radiator determines how much heat it can provide to the room. If the radiators are sized to heat rooms at 80 degrees flow temp they will not heat it adequately at 60 degrees flow temperature.
3945nyu to be precise as stated on one of my previous comments. I’m not fully disagreeing with your comments, but you find the majority of homes are heated to 21-22c quite easily with a flow set at 60.
At the moment I have no rads in the living room and need to get my arse in gear re-fitting them. The kitchen rad provides a mean temperaure in the lounge of 18 deg and the kitch has temp has reduced to about 19c but its cooler at the far end. My living room kitchen are far above average size. Last year we used a 1.2kw quartz heater which heated the living room to a some what comfortable temp but it took time.
Now I bet your wondering why I have no rads in the living room. Well it has taken me over a year to revamp it and put in soundproofing as my health isn’t the best these days. Any way the rads will go on this week and I will replace a bedroom one because its showing signs of rust. So I’m not a tight arse lol.
I said to @Jojoe earlier to turn the flow to 65 and see how he goes and u if necessary, because at the end of the day we all have to feel comfortable in our owns homes. Why were all bickering I don’t know because the savings t be had are only around 6.5-9% contrary to you the press make it out to be.
Have a good evening, got to do a bit of work on anther forum I’m admin 🙂
I’ve upped the flow rate to 64c and it’s done the trick, rads heat up fully and quick.
Thats good news, still a good drop from 78 C
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.
I’ve upped the flow rate to 64c and it’s done the trick, rads heat up fully and quick.
Nice one Jojoe and at least your home is toasty again 🙂
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