I would like to know if someone could give me some advice ? I have
Baxi WM 51/3RS boiler for my central heating system and I am trying t find out if it is running at it's proper setting for the amount o radiators that I have. I know it has been extremely cold recently an also that the boiler itself is old but if I can solve my problem b adjusting then I would rather do this than buying a new boiler if i comes to it that nothing can be done then I guess I will just have t buy a new one. The thing is that since I we have had modifications extension which means that I now have 3 more double radiators and towel rail it seems that the radiators just do not get hot enough an really take a long time to get warm. I have bled the radiator in th bathroom where we always seem to get a build up of air and also trie the pump on different settings ( it seem to work best on it's middl speed setting for some reason I thought it would help turning it t high ) the boiler thermostat is at max and also the room one is se high enough, someone has told me that my BTU setting may need turnin up for new radiators but I cannot find anywhere on the web to tell m how to. I have got a contract with British Gas but I suspect that the will just tell me that I need a new boiler if I call them out
I hardly know where to start! You have identified quite a few issues, all of which need looking at.
Firstly, when the weather is cold, and your house is not getting hot enough despite having everything turned up, is the boiler running continuously or is it cycling on and off on its own thermostat? If the latter, increasing the heat output won't help, because your system is unable to utilise its current maximum output.
Are some radiators getting hotter than others? If so - at very least - your system needs balancing. The process is described in some detail in the FAQ at
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but, basically, it requires the flow to the hottest radiators to be restricted a bit in order to force more flow through the cooler ones.
It's also distinctly possible that your radiators are partially full of sludge - particulatly if there's no corrosion inhibitor in the water. Do they have cold patches about half way along at the bottom? The fact that air is collecting in one of the radiators is also worrying. Are you sure it *is* air, and not hydrogen? [Next time you bleed, collect some of the 'air' in an upturned jam-jar and apply a lighted taper to it. If it burns with a blue flame, it's hydrogen caused by corrosion!]
You should have a small fill and expansion tank in the attic (not the large cold header for the hot water) which feeds the heating system. There will be a feed pipe connected to the bottom of this tank and a vent pipe which comes up the side and curves over the top without dipping into the water. When the system is running, is there any evidence of water flowing out of this vent pipe (known as 'pumping over')? If so, this is bad and needs to be corrected.
So, to get back to where we started, you need to ensure that the system is not full of sludge, that it is not pumping over, has adequate corrosion inhibitor in it, and that it is properly balanced. If that doesn't fix the problems, you then *may* need to look at the boiler output. If the boiler is still cycling on its own stat, you'll need either to increase the size of some of the radiators (or replace them with same sized oned with fins on the back to increase the output) or you'll need to reduce the house's heat losses by improving the insulation. [Have you already got the recommended amount of loft insulation, plus double glazing plus cavity wall insulation plus draft-proofing?]
If the boiler is running continuously, but not producing enough heat, you
*may* be able to increase its heat output. Let's assume that it has been serviced within the last year and is running as efficiently as possible. Somewhere inside the boiler casing there is probably a chart which shows the relationship between gas pressure and heat output. There will be a test point for connecting a manometer to measure the pressure, and a screw on the gas valve to adjust the pressure setting. If it isn't already on maximum, it may be possible to screw a bit more out of it but you shouldn't attempt this yourself unless you are 'competent' to work on gas appliances. One thing which you *can* do without disturbing anything is to use your gas meter to measure the boiler's rate of consumption of gas. With no other gas appliance on, and with the boiler going full chat, use a stopwatch to time a few revolutions of the little red pointer on the meter. The meter should say how much gas is represented by one revolution. You then need to study the calculation on a recent gas bill to understand how to convert cubic feet to kWHrs or, in your case, cubic feet per hour into Kw. You can then compare this with the *input* power rating chart on your boiler to see how near the maximum you are.
Some of the details for measuring the gas rate are given in the FAQ. Invariably boilers are commissioned using the highest setting on the range or permitted settings. However you may find that the boiler is not at the maximum permitted pressure and there is some more available. To adjust the pressure you will need to be familiar with the type of gas valve you have and have the necessary equipment.
Thanks for the advice I will work my way through a point at a time. The boiler never seems to switch off as if it never gets hot enough.
None of the radiators seem to get hotter than others and I have checked they seem to get the same amount of heat all over except for the one in bathroom that I have to expell the what I thought was air, that's a good little tip to use the jam jar I will try that the next time I bleed it.I have checked the expansion tank and the pipe is not dripping, and it is freezing up there so I guess the insulation is working. The wall insulation is another point I need to address as the house did originally have this in the type of lots of polystyrene balls poured into the gap in the walls but I think that a lot of this has blown away when the extension was built.The boiler was last serviced in the summer so it should be in good condition, I will have a go at calculating the power usage at the weekend.
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