My colleague has an Ideal Icos HE 12 boiler that seems to have a recurring problem with condensate discharge.
Approx 1 year after a replacement sump, he has again found a significant blockage on the boiler side of the condensate trap. Having removed the trap he had to use a screw driver to clear a black/silvery crud from the discharge port on the sump.
Does anyone have experience of this kind of issue? Is this a boiler design fault, or maybe an installation problem. Clearly not knowing the install personally I cannot give details, but if there are certain factors that are likely to cause this they could be investigated.
I've yet to try it but I read of people here (who I tend to trust) advocating pouring water into the air intake (or flue gas sampling point)to flush through the burner and out through the condensate drain. Once the heating season is over, I'm tempted to have a go as I can see the transparent condensate trap on my Worcester 28ri has got sediment in it.
Sounds quite like a biological product (bacteria / funghi / yeast), rather implies something wrong with the fundamental design, or perhaps the installation.
Happened on my Worcester-Bosch. I believe it's the (aluminium alloy?)inside of the boiler slowly being dissolved away. Was a problem when newish but wasn't after a few years.
Yes, I do this with my Keston Celcius 25 about every 6 months, having had the condensate exit from the heat exchanger clog with similar slime. It's never clogged since doing this. I pour in a pint quite quickly so it will swill around the bottom of the heat exchanger and hopefully wash away any debris there, and repeat when the first lot has run away down the condensate drain.
I know the Keston C25 very well, having installed it, serviced it and replaced the internal flue a couple of times, and I know there's nothing in there which will come to any harm in doing this. I can't guarantee that for any other boiler though - it's up to you to check in your case. Don't pour in so much you fill the heat exchanger up to the burner or ignition electrode, or you might have difficulty firing it afterwards if the electrode insulator has been soaking wet. The Keston also has a sensor in the U-trap to detect condensate backing up, and if that gets wet, the boiler might refuse to start, although that hasn't been a problem for me.
Yes, don't pour it into the air inlet - on the keston, it would run over the mains transformer and onto the control boards! Must be into the flue exhaust, i.e. following the path that condensate draining back into the boiler from the flue would take.
Good question! My WB flue is horizontal and exits just under the guttering so pretty unlikely to suffer from this but a vertical flue would so I presume the flue terminal supplied with the vertical kit has deflectors to minimise rain ingress.
Andrew, I presume that the flow temperature gets raised when heating the DHW? Too late after choosing my boiler, I was surprised to find that it is not capable of running at two different selectable flow settings. Modifications are in hand! I'd like to be able to run my boiler that low for heating but as it is a retro fit to a system designed around a non condensing boiler, I don't think the cost of changing radiators for higher output ones would be justified simply in terms of fuel saving.
Hot water is from a multipoint instant water heater in this case.
The Keston isn't either, but as the temperature is set with a 100k linear pot to feed a 0-5V signal to the control board for 32C-85C flow temperature, it's dead easy to modify it. I did knock up a replacement front panel which used a motorised pot driven by a PC based home automation, but that's gone (it used a printer port and games port to interface, and those vanished from PCs many years ago). A long way down the to-do list is to build a new interface using a raspberry pi.
I installed the system for condensing operation - the house had no central heating before that. I used a beta release Myson Java heating calculator to work out radiator sizes, and it over-estimated even for condensing operation (it turned out to have pessimistic U-values). I had not intended it to work this low, but in retrospect, I'm really pleased it does as the boiler works just about as efficiently as it possibly can, and I suspect it's significantly increased boiler life too.
I'm controlling mine with an Arduino chosen simply due to familiarity.
My boiler is still under warranty so wanted to avoid connection to the control pot. Instead I am shunting the NTC thermistor that measures the flow temperature. There is a passive Light Dependent Resistor in parallel with the thermistor and the brightness of an LED shining on it inside a black tube is controlled by the Arduino. 0 to 1mA in the led gives all the range I need.
The boiler knob is left turned up high (about 90 of Max rotation) equivalent to about 73 or 74 degrees flow and backed off to a minimum of
60 degrees using the LDR shunt.
The outside temperature is measured with a PT1000 sensor shoved into the air intake section of the flue through a monitoring point. The outside air temperature is used to set the flow temperature with adjustable parameters.
It seems to have coped well over this rather cold weekend.
The next development will be to override the calculated flow temp with an elevated one during DHW demand.
Havn't had that problem with my Vaillant Eco-Tec, but I need to run my flow temperature hotter than that, particularly in this weather. I have a thermometer on the return, but its battery has gone at the moment.
Maybe if they get the design of syphon just right, it flushes enough of any buildup to stay clear. Mine has a "long drop" into a waste pipe.
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