I have an oil fired boiler with base board heating. I get a lot of vibration in the circulation pump when it first starts, which gradually reduces as it runs. The base board heaters generally make clicking noise when they begin to heat up. It has been suggested there may be air in the water lines. I note a shut off valve just downstream from the circulation pump followed by another valve with a drain hose pipe attached. Is it desirable to check the line for any air that may have accumulated and how does one do so giving the valve configuration described downstream from the circulation pump? It is an older system and I have no maintenance manual for the system. Thanks for your assistance. George
Dear Ranger25. Thank you for the information. What you state makes great sense. However, my knowledge of boiler system circuitry is so poor I am uncertain what precise steps I would take to purge the system. Would these steps be appropriate:
1. shut off valve to circuit just downstream to the pump
2. put a hose on the hose bib which is on theshut off valve just above the valve in # 1. Open this valve which will now drain water from the circuit??? Must I open a valve at some other point in the circuit upstream from the bib valve? If so I will have to see if I can find one and gamble on whether it would open or break off in the process. Is the valve the one you mention to open to drain air from the system?
3. How do I now put water under pressure into the circuit to purge it of any waste there??
4. What is the closure step to finalize the process and be certain the system is ready to function??
Sorry to be so uninformed. I hope my steps and questions make sense and your reply is anxiously awaited. Hamogf
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Re: Home Boiler Maintenance
It may just be trash in the lines, also. That is what the valve with the hose attached to it is for, the same as a water heater, it needs to be drained and blown out with higher pressure (not too high) water at least every two years. You will probably have considerable scale and possibly sedimentary buildup in your system due to the fact that routine maintainence has probably been ignored. In order to properly bleed the system of air, you have to find the highest point of the piping system, and if there is not already a hammer arrestor with a purging valve installed, it will need one. Then it's just a matter of cracking the valve a little until you get a stream of water instead of the hissing of the air. Simple as that.
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Assuming you have an oil fired unit. hot and neutral wires on circ should be connected to C1 and C2 respectively. Tstat should be connected to TT which will energize circ on a call for heat and boiler will run based on limits. If you boiler is set for cold start the circ will only run on a call for heat. If you have more than on tstat/zone then you probably have either a zone control box or zone valves and transformer. If that is the case I would defer to a heating professional.
Don't know your specific unit, but in general, heating systems are two-stage devices:
1: Its too cold: the motorised HW/CH valve moved to the required position, and on achieving it, the circulaion pump starts and the boiler is enabled. (The circ pump may start immediately - its not usually important.) The hot water from the boiler circulates through the heat exchanger and/or radiators until the thermostat thinks its target is warm enough, whereupon it disables the boiler, stops the pump and closes/relaxes the valve(s).
2: The boiler is off while disabled. When enabled, it heats the circulating water to a 'high' temperature and seeks to keep it there. If it reaches that temperature, the boiler will cycle on and off as necessary to maintain the set 'high' temperature. (The circulation pump must run all the time the boiler is enabled.) This may be what you're noticing. Additionally, some boilers will run the circulation pump for a little while after being disabled to reduce the temperature if the water in the pipes and boiler.
Your question doesn't say how the pump running corresponds to thee thermostat settings, but if it were stuck on, I think you'd know!
You may have a carbon build up on the ignition probes but this will normally cause a lock out. It may be that the circulating pump is faulty. Ie boiler fires up but due to no circulation it shuts down on the boiler stat and as the heat remains in the boiler it will not fire again until the heat has dissapated. Changing a circulating pp can be done by a confident DIYer but remember due to new legislation the old three speed pps are no longer available. You will need to purchase a modulating pump to match you existing pump. Old and new pump threads and spacing a are the same.
Air in what system?-- The Circulating 'Hot' water?-- or in the fuel? (What kind of fuel?)
Normally a hot water boiler will fire, as long as ther is water in the boiler, So-- are you suspecting there is Low water in the boiler? Can yo hear the water circulating thru the water pump?-- is the water pump running?
Tell us more about what happens when you first give it a call for heat? Do any fans or valve try to start?-- any indicator lights?
Tell us some of the obvious things, and maybe there is a clue in something you tell us or observe.
The problem is probably with the circulator pump or the zone valve, which ever way your water circulating from the boiler is controled.
The water needs to be moved through the boiler and the coils in the Hot water maker to heat water. If this is not happening then no water will be heated.
Check for power and then is the pump is running or the zone valve opening.
I hope that this will help you to solve your problem!
1. You need to fill the entire system with water before you fire it,
boiler AND radiators... Then, you would normally vent as much of the
trapped air in the system as you could... It's not like you are only
going to fill just the boiler and then pump that water through the
There is a temp setting on the boiler, but I don't think that's a
solution. Remember that the water in the system is going to begin
circulating as soon as you start the boiler. So, it will start
circulating when it's cold, and then gradually warm up.
Your problem is not the sudden rush of hot water, it's going to be
filling the system in the first place, and getting the boiler started
before the system freezes up ...
I don't really have any suggestions for you though, other than perhaps
renting one of those construction heaters ... and bring the building
temp up a bit. But there's certain dangers associated with them too...
Carbon Monoxide for one, fire is another (if used improperly).
Just thought of something: Fill the system with glycol based
anti-freeze solution that's designed for heating systems. That oughta
I'm guessing there's not a functioning water heater either at this
point, is there ? If there was, you could possibly rig something up to
fill the system with lukewarm water, and fire it before it freezes up.
2. You don't have a lot of choice. You have to fill the system, fire the boiler & wait.
It is going to take a long time to get the system up to temperature.
Instant circulation is a double edged sword. The upside is you get a
little bit of heat into the water & have it moving making freezing
less likely. The downside is, it's hard on the boiler with that much
cold water coming back you are likely to have condensation.
hi sounds as though the system is sludged up & needs power flushing.the reason is that the water cannot circulate so over heats & pumps into the header tank.
expect to pay approx 350 400 pounds to have it properly cleansed, it will restore the system efficiency.
The other area worth considering is that it could be a faulty pump os that when th eboiler fires it cannot circulate so in turn expands & vents into the tank.
My advise is to arrange for a corgi engineer to sort it out for you.