Balancing heating system, does it cost more?

[dadof3]

New to the site and looking for help.

Recently, I decided to balance my heating system as some radiators where barely getting warm compared to others and after checking they didn't need bleeding, this seemed like the next step.

I have balanced the system and all the radiators get hot at roughly the same rate so it seems to have worked. But due to this, the heating system seems to have to be on A LOT longer than before to heat up the rooms. I understand this will happen due to the slower rate of feed into each radiator but I wasn't expecting so much of a difference.

My question is... Will this cost more in gas?

Seems like a stupid question really but I don't know whether the boiler will retain more heat (meaning it won't burn as long) even though the system is on or whether it doesn't effect the boiler like that meaning it's simply just gunna burn gas like there's no tomorrow.

Also, I think it's important to know that we have a brand new boiler. 1 week old.

Thanks

 

[gmartine]

Sounds like it as your now heating rooms that by your own description had radiators that were barely getting warm.

 

[Chuck]

If you haven't done so already, get a pipe thermometer (ca £10) that you can clip onto the return pipe close to the boiler. As a rule of thumb and assuming it's a gas boiler, if the return temperature ca 50°C or lower then you'll be at best efficiency, if its 55°C or above you'll be at worst efficiency. The difference between best and worst is ca 10% in gas usage.

If the return temperature is typically below 50°C and you want more heat you can afford to open the lock shields on the radiators a little to increase the flow. (When adjusting lock shields imagine a clock face and make adjustments of one-hour or less at a time.) Alternatively, you can run the boiler with a slightly higher flow temperature during this spell of cold weather. The latter is probably worth trying first because it's a single easy adjustment and having the radiators hotter will improve the 'thermal comfort' because radiant heat is arguably more important than air temperature when it comes to how warm the occupant of a room 'feels'. When the warm weather comes you can just dial down the flow temperature again.

Modern boilers don't waste fuel in the way you seem to be thinking. They use just enough gas to heat the system water at the rate that matches the transfer of heat into the thermal envelope of the house. If the house is drawing less heat from the water, e.g. because the TRVs are shutting off, the boiler will 'modulate' and then 'cycle' to reduce the amount of fuel being burned. This is unlike the old coal boilers from 50 years ago where, if the house didn't use the heat it went up the flue. (A significant fraction of the population still believe, incorrectly, that this is how their system works.)

 

[Ric2013]

If I understand you correctly, you have balanced the system and the result is that now the radiators get warm at roughly the same rate. This would be correct balancing assuming the radiators are all exactly of the same output and water content. Since they probably aren't, what you should be looking for are reasonably similar return temperatures from all radiators. Arguably the distinction between the two conditions is splitting hairs in most cases, but I do want you to be aware that radiators heating up in around the same time is not necessarily a correctly balanced system.

Anyway, my concern is another: that you have balanced the system but that it's now universally underheating the radiators which isn't really the outcome I'd be expecting from correct balancing either. I doubt it will affect boiler efficiency that badly, but it means the system isn't really making you comfortable. You should be looking for return temperatures no more than 20 degrees C below your flow temperatures (or 11°Cish if not a condensing boiler). It could be that your pump is not working correctly (unusual), that it is not powerful enough for the job (unusual), on too slow a speed or pressure setting (more likely). Or that you have throttled down the flow though every single radiator (only you will know). Usually, when balancing, you'll end up with at least one lockshield valve being fully open and the rest in various states of shutness so as to restrict the flow only through those radiators that are getting too much flow.

If it turns out you are indeed strangling every radiator flow down, then you may have a balanced system but with insufficient flow. Perhaps every radiator is running at 60/30 (for sake of argument) and hence is now too cold to give a good heat output?

How is balancing related to heat outputs? In a nutshell, you want to have your radiators a certain temperature above your desired room temperature. Traditional (obsolete) systems running at 80/70°C have an average temperature of 75°C, which could be around 55°C above the room temperature. An ultra-modern system may run at 50/30 and so be only 20°C above the room temperature, which is fine but if we run the same size radiator at this lower temperature, the heat output from it will only be a quarter. The boiler will also use less gas and (if a condensing boiler) will run more efficiently if the radiators are running cooler, but your rooms won't heat up if the system wasn't designed to be run this cool.

The above relates to balancing because if we had a system with two radiators designed to be running at 50/30 and we re-balanced one radiator from 50/30 to 50/40 to the detriment of another radiator now running at 50/20, the output of the one radiator would go up 30%, but the output of the other would fall 30%. The boiler would still be using roughly as much gas (possibly a very little more), but the heat would be distributed differently between the radiators.

If, like most of us, you have a system with a condensing boiler but can't get enough heat output from your radiators if you run them at ultra-low temperatures, there is (usually) a very simple solution. You balance your radiators to run at, say, 75/55°C ish. That may not give good efficiency at those temperatures, but you'll only run it that hot in mid-winter. When the weather isn't quite so cold, you simply twiddle the flow temperature control down on the boiler (most boilers have this readily available as a user-setting) and run the system at a less hot but more efficient temperature. It's a compromise, but it ensures high efficiency in all but the very depth of winter (and, as Chuck has pointed out, even then, you'll only lose a few percentage points).

Not sure if this is helpful or drivel. I can only apologise. Time I went to bed, probably...