Is it condensing?

grn99

So, am I right in thinking that if a condensing boiler is emitting plumes of steam from the flue it isn't condensing? The boiler is a Baxi Ecoblue 19 Advance Heat, The flow temp was set to 60, the return flow to the boiler (measure by a contact probe) is in the 40's yet the steam is produced. I cannot see anyway to check if the boiler is condensing on the boiler itself - there are no inidcation panels on this basic model. Can a condensing boiler go faulty in some way and not condense, even if the return flow temperature is low enough?

InvertedVee

Hi @grn99. Even in condensing mode, a boiler won't condense 100% of the exhaust vapour, so you'll see a plume on cold days, so nothing to worry about.

If the boiler is working hard, the plume will be bigger.

In many situations, the most efficient way to heat a home is to get the boiler to work gently for long periods (a combination of low flow temperatures, sufficiently large radiators, modulating controls, setback temps 1-2C beneath day temperatures, good insulation etc). You should then see the flue just 'breathing out' condensed vapour rather than blasting it out.

Ally_E.

Look out for density of steam, if it's dense and no transparency, it's not condensing. More light steam with transparent appearance in places, its condensing 

diystarter7

Hi OP

Of all the years we have had our boiler, the boiler does exactly what yours does.

The flue is on the side wall and a cold wind down that way, looks like a heavy smoker at times and only happens during cold spells like now, I'm not sure but when the boiler has been on for a while I think it stops. However, we've never had a problem with our boiler

If your boiler was losing water, the water level would fall and if it fell to a min, it cuts out as ours did when we had a fault with one at another place.

When turing on the boiler CH and at times hot water and its cold, you will see it and at times seems like quite a lot but it depends where you are seeing your flue from and if there is some wind it travels across then up.  Again all of our boilers have done that but will see if they keep on doing it as the day goes on and temps drop to freezing as in warmer weather you can see the steam.

Thanks

Mstty

On a day like today at -2oC(that's here) the steam may look more dense so may not be the best day for a visual check.

grn99

Thanks everyone. I did wonder if it was maybe as much to do with the cold temps and how much/how dense the vapour is... will keep any eye on it and take on board all the good points made. Trying to run it lightly throughout the day time using the programmable stat at 16 and as low a flow temp as I can get away with and still be effective in providing some "gentle" heat. Thanks again.

[Deleted User]

and as low a flow temp as I can get away with

What flow temp have you set? I am surrounded by houses emitting exhaust plumes high into the still sky. My boiler flow temperature is set at 55C and all I can see is a wisp of moisture coming out of the exhaust flue. My boiler’s water trap also empties about once every 2 hours.

matelodave

Have you tried reducing the flow down to 55 or even 50 to see what effect it has on your gas consumption, comfort level or even density of the plume.

In the end it's what suits your boiler, your heating system and your comfort level - most settings are adjustable and with a bit of tweaking you can optimise them to suit your situation. If you can get your boiler running a bit longer at a lower tempearure and reduce its cycling then you'll improve its efficiency (just like cruising up the motorway at 50mph rather than blatting along at 70-80 and having to keep slowing and accelerating)

It also helps if you've been monitoring and recording what is going on before you tweak and after you tweak and making sure that you only do one thing at a time and give it a day or two to settle between adjustments so you can evaluate whether you've improved it or not. Random twiddling doesn't really help you understand what happens and why.

Dont get hung up on specific temperatures - they are a bit of an indicator for initial settings but in the end just adjust the controls so they suit your requirements eg if its 5 at the moment then knock it back to 4.5 to see what happens. The aim should be to get the boiler working at the lowest temperature you can commensurate with the comfort levels that you require and a reheat time thats acceptable to you and your lifestyle.

Ally_E.

If you don't have a digital display to see what the flow temperature is, most boiler instructions will tell you what the settings mean. Or you could get a pipe thermometer and test.