vaillant ecoTEC plus 615

bilibala

Hi ! guys,

I need some advice before I call the engineer out. I had the above boiler installed last November.

The problem I'm getting is when the room temperature is reached (room thermostat set at 19 degrees) the boiler stops firing up and fires up again when the temperature drops below that setting, but my bolier doesn't fire up again until the bottom half of the radiators gets cold. The boiler can remain off for up to an hour before it fires up again and the house gets very cold sometimes I have to have a blanket on me. I've tried increasing the room temp to 22 degrees but still get the same problem. I don't want to increase the temp too much as I want to save on fuel. oh ! and the thermostat is working properly. Appreciate any advice out there, thanks!

bilibala

bambibashercol

Any error codes on the boiler?
Could be a few thing but would need to be at the boiler and to check the controls.
Has this problem been there from when the boiler was installed or just started happening?

andrew-b

Sorry but whats the problem as it sounds like it's doing what it's meant to do? The whole point of the thermostat is it maintains the temperature of the air surrounding the thermostat at whatever temperature you set it to. If it falls below your set temperature (19c in your case) heating comes on and stay on until the temperature reaches that temperature again. The temperature within the radiators is irrelevant to the setting on the thermostat.. all the thermostat understands is the temperature next to it.

Where is the thermostat located? Do you have a thermometer that you could place by it to check the temperature to confirm it's working and see how the temperature varies around the house?

Do you have thermostatic radiator valves (TRVs - big valve at one end of radiators with small vents on it and numbers on the side.. usually 0 * 1 2 3 4 5) in the rooms you feel cold in? If you had a new boiler last year i'm assuming you would have at least ones in bedrooms. What are they set to? Turn them all until they are on their maximum settings..if your then too hot turn in a room turn the TRV on the radiator in that room down by about half a number and try that and see if it's still too hot..if yes turn down more ..and so on.

TRVs are basically thermostats for individual radiators . If the main room thermostat is set to 19C but a radiator TRV is set to a temperature that corresponds to 17C (for the sake of argument lets say 3 on the TRV where a higher number corresponds to higher temperature) then the temperature in the room of that radiator will never reach 19C as the supply of heat to that radiator will be cut when it reaches 17C.

Try the above before getting anyone out and let us know how you get on.

bambibashercol

Am I right in thinking that you set the temp on the stat. Boiler fires up then when temp reached the boiler shuts down and does not fire up even when below the set temp?
Is it freezing in the room with the room stat? or all around the house?

andrew-b

bambibashercol wrote: »

Am I right in thinking that you set the temp on the stat. Boiler fires up then when temp reached the boiler shuts down and does not fire up even when below the set temp?
Is it freezing in the room with the room stat? or all around the house?

But they said

bilibala wrote:

fires up again when the temperature drops below that setting

?

bilibala

bambibashercol wrote: »

Any error codes on the boiler?
Could be a few thing but would need to be at the boiler and to check the controls.
Has this problem been there from when the boiler was installed or just started happening?

This happened about 2 months after the boiler was installed but I didn't have time to
sort it out until now when I need the heating. Anything to do with something called pump over run...??!!

bilibala

andrew-b wrote: »

Sorry but whats the problem as it sounds like it's doing what it's meant to do? The whole point of the thermostat is it maintains the temperature of the air surrounding the thermostat at whatever temperature you set it to. If it falls below your set temperature (19c in your case) heating comes on and stay on until the temperature reaches that temperature again. The temperature within the radiators is irrelevant to the setting on the thermostat.. all the thermostat understands is the temperature next to it.

Where is the thermostat located? Do you have a thermometer that you could place by it to check the temperature to confirm it's working and see how the temperature varies around the house?

Do you have thermostatic radiator valves (TRVs - big valve at one end of radiators with small vents on it and numbers on the side.. usually 0 * 1 2 3 4 5) in the rooms you feel cold in? If you had a new boiler last year i'm assuming you would have at least ones in bedrooms. What are they set to? Turn them all until they are on their maximum settings..if your then too hot turn in a room turn the TRV on the radiator in that room down by about half a number and try that and see if it's still too hot..if yes turn down more ..and so on.

TRVs are basically thermostats for individual radiators . If the main room thermostat is set to 19C but a radiator TRV is set to a temperature that corresponds to 17C (for the sake of argument lets say 3 on the TRV where a higher number corresponds to higher temperature) then the temperature in the room of that radiator will never reach 19C as the supply of heat to that radiator will be cut when it reaches 17C.

Try the above before getting anyone out and let us know how you get on.

The problem is it feels the temperature has dropped well below 19 degrees before it fires up again and I feel cold in the warmest part of the house which is the living room. All TRV's are on max, the thermostat is located in the hall way. I did not have this problem with the old boiler which was about 20yrs old.

andrew-b

Did you have a powerflush with the boiler change (if not maybe the radiators and pipes all sludged up - hence colder at bottom) and was inhibitor added to prevent corrosion (installer should have filled in back of the boiler's log book with this info)? If a powerflush wasn't carried out was a chemical flush done instead? Were the TRVs new with the boiler?

Another theory is maybe you have an airlock somewhere in the pipework.

To clear airlocks you can use the pump of the heating system to force water all to a single radiator at a time - any air in the pipes enroute from/to the boiler will be forced into that radiator.

1) Turn off all the radiators at the TRVs (or valves where no TRV) except one - opening the valve on the one radiator fully.
2) If it's possible on your system and you know how turn the pump upto it's highest setting (if it's a combi the pump is in the boiler itself so may have to consult the manual if there is an option to do this).
3) Turn up the room stat full whack (30c or more) and make the heating come on at the programmer (permanently on for now) and turn the hotwater off at the programmer too.
4) Boiler should fire up hopefully.. give it at least 5 minutes (maybe 10 at most) and feel the radiator that's turned on to check if it's hot all over. If there is air in the system then the boiler may make some strange noises..sounds quite alarming to the uninitiated but don't worry it will be ok and should calm down after a while.
5) Then move onto the next radiator .. turning off the previous radiator and turning on this next rad, wait 5-10 mins and check.
6) Repeat step 5 one radiator on at a time until all rads been done.
7) Once done ..turn the thermostat down to your preferred setting and turn off heating and hot water completely at the programmer - so the timer isn't going to turn it back on during the next stage. Give it a while to all cool down (i'd give it 15mins or so - check the rads/pipes dont feel hot).
8) Whilst waiting to cool down go round and open up all the TRVs/valves fully again.
9) Once cool now go around with your radiator bleed key and bleed off any air from each radiator (see http://www.ultimatehandyman.co.uk/bleeding_a_radiator.htm if you don't know how - if it's a combi boiler then repressurise the system at the end at mentioned on that webpage). If no air comes out then it's unlikely there was an airlock in the first place so probably something else to blame.
10) Once your done set the programmer back to what it was before - if you turned the pump up set back to what was before too.

The above will take you quite a while ..whether it will help or not depends whether or not there is an airlock in the first place so it could be a waste of time and gas.

Now either test the system and see if it's any better or leave until next time it's set to come on.

Canucklehead

Hi

The boiler is under warranty. First line of attack is the installer, who will look at it, and if needed talk it through with Vaillant . If it can't be sorted over the phone then Vaillant will book a warranty call.
A bit like a another thread on the forum a few days back. (problem was sorted)

GSR

bilibala

andrew-b wrote: »

Did you have a powerflush with the boiler change (if not maybe the radiators and pipes all sludged up - hence colder at bottom) and was inhibitor added to prevent corrosion (installer should have filled in back of the boiler's log book with this info)? If a powerflush wasn't carried out was a chemical flush done instead? Were the TRVs new with the boiler?

Another theory is maybe you have an airlock somewhere in the pipework.

To clear airlocks you can use the pump of the heating system to force water all to a single radiator at a time - any air in the pipes enroute from/to the boiler will be forced into that radiator.

1) Turn off all the radiators at the TRVs (or valves where no TRV) except one - opening the valve on the one radiator fully.
2) If it's possible on your system and you know how turn the pump upto it's highest setting (if it's a combi the pump is in the boiler itself so may have to consult the manual if there is an option to do this).
3) Turn up the room stat full whack (30c or more) and make the heating come on at the programmer (permanently on for now) and turn the hotwater off at the programmer too.
4) Boiler should fire up hopefully.. give it at least 5 minutes (maybe 10 at most) and feel the radiator that's turned on to check if it's hot all over. If there is air in the system then the boiler may make some strange noises..sounds quite alarming to the uninitiated but don't worry it will be ok and should calm down after a while.
5) Then move onto the next radiator .. turning off the previous radiator and turning on this next rad, wait 5-10 mins and check.
6) Repeat step 5 one radiator on at a time until all rads been done.
7) Once done ..turn the thermostat down to your preferred setting and turn off heating and hot water completely at the programmer - so the timer isn't going to turn it back on during the next stage. Give it a while to all cool down (i'd give it 15mins or so - check the rads/pipes dont feel hot).
8) Whilst waiting to cool down go round and open up all the TRVs/valves fully again.
9) Once cool now go around with your radiator bleed key and bleed off any air from each radiator (see http://www.ultimatehandyman.co.uk/bleeding_a_radiator.htm if you don't know how - if it's a combi boiler then repressurise the system at the end at mentioned on that webpage). If no air comes out then it's unlikely there was an airlock in the first place so probably something else to blame.
10) Once your done set the programmer back to what it was before - if you turned the pump up set back to what was before too.

The above will take you quite a while ..whether it will help or not depends whether or not there is an airlock in the first place so it could be a waste of time and gas.

Now either test the system and see if it's any better or leave until next time it's set to come on.

hi! andrew,
The radiators are not the problem as they are hot to touch from bottom to top when the boiler is on. I don't understand why the boiler has to wait till the radiators are cold before it fires up again...

bambibashercol

Have you got a wireless roomstat? If so it could be struggling to contact with the reciever.
I don't think its a problem with the boiler but with the controls. Get the installer to check zone valves and stat.