Some questions about balancing central heating

[Thedeester1]

Firstly hello this is my first post.
The back ground: I recently bought an old house. The heating system was intact but the boiler wasn't working (heat exchanger leaking).The boiler was replaced with a straight replacement Ideal Condensing boiler. At that time there were no radiators on the walls so a system balance was Impossible. Now the house is getting something like finished I found I was getting astronomical gas bills.

From Instructions found on this site I set about DIYing it. Im an electro mechical engineer in a Glass works so I can manage to follow instructions and have Multi meter with thermo couple Input as a Thermometer.


First Question: To achieve the 10 to 15 degree Drop across the rads every lock shield is almost closed. They are the danfoss ones with an Allen screw adjuster. I would say that none are open more than 1/8 of a turn. Is this normal?

Second Question: I can only just achieve the 55degrees return leg temp (for Condensing) at the boiler and the pump is running at full speed. To Get this I have to set the boiler to no2 on the boiler stat. With the boiler at full heat I get around 75deg out 65 return. Is the pump at fault? If so why am I having to restrict the radiator lock shields so much?

Thanks in advance for any help.

 

[Dotty]

start again using this method....

 

[Rickster123]

start again using this method....

arty: We love this sticky!

 

[Thedeester1]

start again using this method....

That's pretty much the method used. I have done the whole thing again and the results are still the same. None of the lock shields are open very much to achieve a temperature differential across the radiators?

I did find that the towel radiator in the bathroom wasn't getting hot because I had closed the lock shield too far. I opened this a little and now the best differential I can get is 8deg. Could this be because the pump is too fast and there is too much flow?
The reason the pump is on full is to try to get the boiler return below 55deg as was stated in the post I read.

 

[happyflyer]

You need to know a little more about Lock shield valves, they are not linear in their operation, they are cheap and nasty, a good idea is to take a LS valve in you hand, open it about 1 turn and blow through it, then 2 turns and blow thorough it, then 3 turns until its fully open, you should notice that at about 2 turns there is little difference in the flow rate than when fully open, in other words once a LS valve is passed half open it is virtually fully open, it is a fact, normally rads near to the boiler needs to be almost shut, depends on pipe sizes and pump pressure and a lot of other things. A good designed system will need very little balancing but a system which has long runs with small diameters will be a pig, don't be surprise if some LS valve need to be only half a turn open and they will make a noise as the water screams over the seat, its like tinnitus. People adding rads to a system not knowing what's under the floor will make a mess of it for you too.

Have Fun

 

[happyflyer]

start again using this method....

CC "Croppie Copyright" not available in hardback and out of print at the moment :sleeping:

 

[Mike Jackson]

Firstly hello this is my first post.
The back ground: I recently bought an old house. The heating system was intact but the boiler wasn't working (heat exchanger leaking).The boiler was replaced with a straight replacement Ideal Condensing boiler. At that time there were no radiators on the walls so a system balance was Impossible. Now the house is getting something like finished I found I was getting astronomical gas bills.

From Instructions found on this site I set about DIYing it. Im an electro mechical engineer in a Glass works so I can manage to follow instructions and have Multi meter with thermo couple Input as a Thermometer.


First Question: To achieve the 10 to 15 degree Drop across the rads every lock shield is almost closed. They are the danfoss ones with an Allen screw adjuster. I would say that none are open more than 1/8 of a turn. Is this normal?

Second Question: I can only just achieve the 55degrees return leg temp (for Condensing) at the boiler and the pump is running at full speed. To Get this I have to set the boiler to no2 on the boiler stat. With the boiler at full heat I get around 75deg out 65 return. Is the pump at fault? If so why am I having to restrict the radiator lock shields so much?

Thanks in advance for any help.

Plenty of possible issues here.

If the new boiler is the same output as the old one it is likely that it is oversized for the property and you will struggle to achieve the correct temperature differential.

If the radiators are undersized you will again struggle to get the required differential.

I can't fathom out why you have turned the pump up to try and reduce the return temperature. You may get a lower flow temperature by sending the water through the boiler faster but that is what the boiler stat is for. With a slower pump speed the water has got more time to lose it's heat.

 

[scottishgasman]

Firstly, 20*c Differential is the target. More often than not your not going to make it there. Its also subject to change, IE: if you did achieve 20*c diff, while the weathers cold, say freezing outside, and cold inside, you will almost certainly not have a 20*diff once the house has heated up as the raidiators will not be loosing heat as fast to the room, same goes for when the weather is a little warmer.

assuming its a heat only boiler and you have an external pump with selectable speed, reduce it down (then rebalance) the water moving slower through the rads will have more time to tansfer heat to the room thus having a lower return temperature.

And as said already, the radiators might not be big enough to give a 20*drop across them, balance it as best you can so that the rooms are heating evenly and see how you get on from there

 

[josh]

Another way to reduce your fuel bill is to not have it on as much and put a jumper on?
I can't see balancing is going to save you the amounts you seem to think it will?

 

[SimonG]

Turn boiler stat down, that will save money.