jrldallas wrote:
I just want to have some ideas so that when I get someone round I can have an "educated" discussion with them.
Bengasman said:
You are wasting your time, and more likely than not pis off any decent rgi that you manage to get in the door.
I don't work that way. Many of my best customers appreciate being told what's going on so they understand what I'm doing and why. With old cronky systems such as jrldallas describes, there are a lot of unknowns.
The problems of Suprima 120s, auto bypass valves and resistive clogged systems aren't even slightly hard to explain to a fairly bright electrical engineer. It would take
several minutes.
If I had a problem and asked for explanations of what the issue might be, and was told I probably had tried to take a miserly approach so it was my fault, I'd feel the need for a pencil, and an urge to poke it through the eyeball of the idiot who'd decided that I needed to be insulted.
(I would hope that he would then see the point.)
Similarly, if I were told that I shouldn't be asking about my system, or bothering my little head with it, injury might be imminent, but not to me.
Are you seriously suggesting anyone would agree to just keep paying without knowing what for, or how much might be needed to complete the job?
I know Tony (Agile) and Ben personally, and can't imagine that they would deal that way with me if my problem were something they could help with.
I don't know what this forum does to otherwise rational people!
JRD - your pump's too small, even a 15-60 would be marginal, and the pipework on a typical Suprima 120 installation is definitely on the small side. Really they're better with a "small commercial" pipework approach rather than "small domestic".
The problem is generally of getting the heat out of the box quickly enough, especially when valves around the system close.
Sludge obviously makes things worse.
A bypass is important to an S120. It has two functions, one to provide a heat-losing route, and the other to allow enough flow through the boiler that its own thermostat sees a representative temperature quickly, so can control the boiler.
An
automatic bypass is one which opens at a set pressure , so (from the pump's pressure/flow curve) you can guarantee a particular minimum flow through the boiler at all times. If you have a fixed short-circuit type bypass, it reduces the pressure (like voltage) when you don't want it to, and may not allow enough flow (current) when IT is the only route available.
Flow problems in heating systems are difficult in that you can't stick an ammeter in, or tell what pressure (like voltage) the pump's producing. But you CAN measure temperatures and with some thought work out where the problem appears to be. Eg, is the boiler really overheating, or is it faulty...?
See - I could have said all that in less than 2 minutes.