baxi 105he

[grizzler]

just before xmas had an old wall mounted boiler replaced by a baxi 105 HE combi boiler placed in bathroom (where old water tank was)...
forgive my basic understanding but ...it seems the rads are getting very hot now ...if i reduce the CH temp setting on the boiler to about 3 oclock (bout 40 degrees??) then once the room thermostat downstairs(an old honeywell control) calls for heat the Boiler ignites and the temp leds light up to @ 40/50 the Boiler flame LED will then go off and CH still in operation (ch led stays on)...SO FAR SO GOOD!!
HOWEVER ..if I alter the boiler CH temp to @ 6 oclock or just over) ...(70 ish degrees??) once the room thermostat calls for heat the boiler lights up and heats up to @ 70 degrees but the boiler ignite light does NOT go off until the room thermostat stops calling for heat...and the CH Rads just get hoter and hoter!
however if while this boiler is still heating the CH water up over and above what I think it shhould be doing and i turn the temp gauge up fully (only for 10/15 secs ir so) the extra led lights up then when turn it back down to 6 oclock the boiler STOPS heating the water and the CH led stays on.
It seems to me that at the higher setting whatever monitors the water flow temp in the boiler itself isnlt recognising the heat of the water and continues to heat ...but the actual turning of the gauge up then down causes the boiler to recognise the temp of the water...so switchs the heater off

I also have two trv's in the two upstairs bedrooms but not on the bathroom rad where the boiler is ..

i also have a cold spot in the room where the thermostat is ...even tho i had a 'power flush' ..
I intend to get the guy back to look at that and want to know if I am valid in telling him the boiler temp controls arn't working correctly..

Any help on this would be appreciated..think i've covered everything

THANKS GUYS

 

[bster]

The boiler wont (not designed to) switch off at 70 degrees, it will just maintain a constant 70degrees flow temp and as you say the room stat will determine the switching on&off (unless there is a boiler fault which will trigger the safety\high limit stat.)

 

[grizzler]

oh rite .that would explain it I suppose!!!
still don't get it tho ..why would that only be at 6 oclock on the temp gauge setting...seems pointless having the gauge if thats the case ?
and why does it switch the boiler ignite led off if i turn it up full then turn knob back down to 6 oclock wher it started from...like i said it only a rudimentary test so i'm not too sure if its even valid
and i'd rather make myself look an idiot on here than in front of the plumber ..if you get my drift ...

if you could explain the way its supposed to work it my help my basic understanding ...keep it simple tho please!!

cheers

 

[kevplumb]

if you could explain the way its supposed to work it my help my basic understanding ...keep it simple tho please!!

go get it floyd

 

[grizzler]

do i take it you mean it aint that simple ...didnt think it would be...or you guys wouldn't get paid as much ..supose i could always ring baxi up?...although if their 'help lines' anything like ours I could be wasting a lot of time pressin '1' to continue !!
just stumbled on this site...and you guys seemed helpful so thought ild give it a go ...

 

[kevplumb]

no disrespect son yer append to cop our resident apprentice

 

[grizzler]

none taken whatso ever ...like i said i'd rather look a numpty on here ..cus no-one knows me

and although it says so in his tag line i'm never too sure of the banter that goes on between 'resident posters' on a forum ...i know i read others where you can tell whats 'going on ' after reading for a while ...well most of the time anyway ....maybe i should have read this forum a little longer to TRY to get the gist of what goes on.

going back to my 'issue' ...can anyone elaborate ..cheers

 

[baxpoti]

Your boiler is doing what it should be doing, providing its modulating. (observe flame picture changes).

It can easily maintain a low temp and hence flame will eventually go out.

On a higher setting it will modulate down when it reaches set position, and continue to 'tick over'.

If you briefly increase the temp and then decrease, the flame will go off until the temp drops to the set position.

 

[grizzler]

thanks for the reply ..when you say modulate down do you mean that the flame LED will dim /flicker ....ow do i check this
all i know is its seems to be getting the rads too hot last week or so ..and i'm sure when i switched the boiler stat down just after it was fitted the rads wer not as hot ...??
i just thought i was wasin energy (and money!! ) as the the rads get so hot with the latent heat and that this extra heat meant a larger temp range in the house ...which i didn't want to have ..
ie the hotter rads would take the average temp way over the room stat temp setting ...turning the room stat down means the house get to cold before it kicks the CH back in ..
seems like i wonlt be able to get the control i wanted then?

 

[kevplumb]

.when you say modulate down do you mean that the flame LED will dim /flicker ....ow do i check this icon_confused.gif

no not the led the flame will reduce/increase in hight according to the demand on the boiler

 

[grizzler]

oh right ..that makes more sense then ...i realy oughta learn to read beterer than wot i am doin i suppose to check this i need to investigate more ...however i dont think i will do as it seems from what you guys say all it as it should be..still bloody hot rads tho!!

would a modern room thermostat/7 day timer give me a more 'even' room temperature ...what sort of costs ?are they easy to fit etc...i dont want a radio one ...dont trust wireless (i work with pc's!!)

thanks anyway guys its made me feel a little easier

 

[baxpoti]

The boiler heats water
The water heats the radiators
The radiators heat the air

The boiler stat measures water temp
The room stat measures air temp

Turn the boiler stat to max* and the (poorly sited, antiquated?) room stat to lowest setting as comfortable, normally 20 deg (women seem to like 26deg)

*Note max condensing mode (most efficient) is 63deg

 

[grizzler]

thats how i thort it worked . ..26 deg unless its my mum when its 36 deg!!
as for the 63 deg for max efficiency ...how the hell do you set that accurately..i have enough trouble with the fluctuating heat as it is!!