Would it be accurate to say, in general, that weather compensation on condensing boilers lowers flow temperature as outside temperatures rise?
I ask partly because my boiler's weather compensation has a number of 'slope' settings, presumably to compensate for levels of insulation etc. Would a a better insulated home, requiring a lower flow temperature, result in a more efficiently operating boiler?
One thing I do recall about them under these conditions is that the condensate drain has a nasty habit of blocking as the water freezes on the walls of the pipe until it blocks. Then the boiler interlocks out.
Yes! The heating system will be able to much more closely match it's output, to the demand of your home. Which means that rather than your boiler starting and running flat out, until the demand ends, knowing what what the actual demand is, it can precisely match it, with no under or overshoot.
Rather than the creaking of pipes, as the boiler fires, then switches off, the flow of heat is much better controlled, by the boiler being precisely modulated.
Yes! For my system, you set an initial slope, but the system itself 'learns' and adjusts it's slope itself, to fine tune itself.
Yup generally. It will use the lowest flow temperature it can to get the required result. So that in turn may lower return temperature and so flue gas temperature as well.
Generally yes.
Not sure what this has to do with weather compensation as such. Better efficiency will tend to produce more condensate rather than less, making freezing of the condensate pipe less likely.
However frozen condensate pipes in general are not good. These are usually a result of a failure by the installer to do an adequate job making sure that it does not happen. Following the installers instruction manual would be a good start in many cases!
So transition to a much larger pipe before you exit the building. If running through a cold space like a loft, then insulate it, and if need be provide trace heating. Don't do daft stuff like discharge condensate onto a roof, or drop it out of a pipe exiting an external wall as if it ware and over pressure vent pipe.
I've routed the condensate via a washing machine hockey stick trap into a conveniently located internal soil pipe on occasion. Almost zero chance of freezing unless the house becomes derelict.
Yup, I did similar - it runs into the 50mm waste pipe that collects the outlets from DW, and WM etc.
True. It's odd how everyone will tell you you must use a pro to install a boiler - yet the instructions on how to do this without problems very often ignored. If the wealth of posts about frozen ones are anything to go by.
Had a once workmate who is a bit anal about some things tell me it shouldn't go into a drain without treating it first. Pollutes the sewers or something. And described some device he's bought at vast cost to make it safe. But my boiler instructions give details of using a foul water drain, rain water one and a soakaway. And a German boiler, so often more 'green' about such things.
+1
It is mildly acidic - about as much as lemon juice. So there is usually a recommendation that it be mixed with other waste water if being sent to a metal pipe.
However I can't see a problem with it diluted at sewer volume!
I've done that.
Sometimes the pressure of say the washing machine draining does seem to push up to the boiler and creates a bubbling sound in (what I assume to be) the condensate reservoir. I've been meaning to look at a way of preventing that happening - any suggestions?
I trimmed down the height of the stand pipe waste for the WM, and put a swept tee on the top. Hooked the WM waste hose into the top of the tee, and then fed the 21mm condensate drain into the side of the tee using a boss to convert the sizes.
So the top of the pipe is still open to the air, and the trap on the standpipe is still a significant drop below. The condensate is being added to the pipe above the outlet of the WM waste hose that pokes down the pipe a bit. So there is no air seal, and the WM waste does not directly go near the outlet from the condensate drain.
It has always worked nicely.
Use a dedicated washing machine trap. Take the condensate pipe into the top of the upright and don't seal it. Start by putting a cupfull of water into the trap to provide a water stink seal to prevent sewer gases escaping.
Umm. Not to be over picky but, shouldn't these devices include a tundish?
There has to be a visible air break and a 75mm seal but ISTM that's met with a pipe into the top of an open w/m hockey stick. AFAIK nothing says you need to be able to *see* if there's condensate coming out ;)
On my Vailant boiler it says
Condensate discharge systems
It is not necessary to provide extra traps in the discharge pipe as there is already a trap inside the boiler. Fitting an extra trap may cause the boiler siphon to work incorrectly.
The permitted diagrams for the condensate discharge show one method of connecting to a sink waste BUT ONLY USES ONE trap for both and the condensate is connected before the trap, presumably so the pipe is open to the air via the sink plug and sink overflow holes.
Ah. I was thinking more about the situation where the installer has linked the boiler pressure relief valve piping to the condensate run off.
No requirement. The need for a tundish occurs when you have the potential to back contaminate the mains water supply. Typically on an unvented cylinder fed direct from the main, the over temp and over pressure relief valves would discharge via a tundish. That provides and air gap and also a visible indication that water is being passed.
Condensate is just a by product of combustion - no derived from the mains water.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.