boilercorrosionheatinghydronicvalve
I have a hydronic heating system in my house, and I noticed a valve on a pressure gauge on the side of the boiler is extremely corroded (see 3 pictures below).
1) Is there any purpose for this valve other than for removing the pressure gauge?
2) Is this a huge/expensive/messy accident waiting to happen if I don't do something about it? If so, what should be done? I'm a somewhat handy DIYer but don't know much about boilers, is this something better left to an expert?
As long as the boiler is capable of providing enough hot water through the system to heat the whole house if necessary you shouldn't have a problem.
What you are proposing is a "coarser" version of thermostatic valves on each radiator and that is perfectly safe for a combination boiler.
I don't think you need return valves.
Make sure that you leave one radiator "open" (usually the bathroom one) so that there is some flow around the circuit.
By the way the fact that it's a combination boiler is a red herring. The "combi" bit refers to the hot water heater, the central heating aspect is pretty much the same as a "standard" boiler with integral pump.
Update
If you want to control the times each room is heated independently you can get combined timer and thermostatic radiator valves - My Greener Home has some for example.
I'd try something that has a single lever to turn. These are generally easier to grab. And while you're at it, a similar replacement for doorknobs can be helpful. A quick google turned up this:
Best Answer
NO, the valve is only there for isolation of the gauge. Gauges like that have a high failure rate (for various reasons) and often need to be replaced "on the run"; that is, while the boiler is still in operation.
The construction of that type of gauge uses a Bourdon Tube, in which the process fluid (e.g. hot water, steam) is actually present inside the gauge. Failure of the gauge could indeed be messy and expensive, if you could not isolate it.
For both cases, the valve is an important system component.
It is a simple job, but depending on application and your locality (plumbing/boiler code) it may not be legal for someone other than a pro to do it. Check with the local Authority Having Jurisdiction (AHJ).