Would like your comments on this scenario:

Boiler running and accumulator gets to 80 degrees top and bottom.
Boiler throttles back with unburnt wood still in it.
Boiler flue cools and laddomat pump is switched off by flue thermostat.
Central heating comes on and accumulator cools.
Boiler does not come back up because the flue is still cool.

So is there anyway this situation can be avoided i.e. something brings the boiler back up to utilise the unburnt wood still in it?

Thanks all
Scotch

Finny's right Scotch, It's where art meets science.
What I do for example:- is on a cold winter evening when the CH is running and the house is up to temp and the store is approaching 70 degrees, I start to "throttle back" the ammount of wood I load in order to end the burn with the store at 80/90 degrees. This sees me through the next day, before I light up again.

Hi orangemannot,
I chose a model with a Lambda sensor, and I'm glad I did. It does control the burn well. The way I understand it is, the sensor controls a couple, ( in my case ), of motorised air intake dampers on the front of the machine, which in turn produces a fiercer or slower burn as required.

Mike

My wood was free, so I figgered the extra cost of the lambda sensor models was not justified...... like an extra £2000.00 min from what I remember.
The greatest advantage to the lambda sensor that I see would be in the start up phase as I find it odd that I cannot use the blower fan to get the boiler to light up quicker, it appears to blow it out rather, only being able to operate at 100% until the flue gets too hot and it throttles back.
I wonder if some of the models with the suction fan are better in this respect, though how long a fan impeller unit lasts running in the flue gases?
cheers.
PS
When lighting, as my flue was not installed high enough ........when I close the top door as instructed in the instructions, & leaving the bottom door open, per the instructions, she "steaughs" until I open the top door then "woomph"
The only time she lit up properly was the other night when there was a good strong wind coming from a particular "art" which blew straight in the bottom door.
So some remedial works required this summer
PPs
Owlman, what one did you install?
cheers
M

I don’t have a laddermat instead I have a recirculating pump that comes on when the temp at the top of the boiler is more than 6 deg higher (user setting) than the return temp (taken at the bottom inlet of the boiler).

So, mine works like this:

• Boiler burns. When boiler reaches 65 deg (user setting) TS heating pump starts and TS warms up - if boiler temp goes below this 65 deg, pump stops.

• Boiler water temp reaches 85 (a user setting) and its fan stops (happens when it cannot transfer enough heat via coil to TS (TS at around 65)).

• With fan off, TS heating pump continues. Still to work out exactly what the trigger is to begin fan but it simply re-starts when more heat is needed, the TS continues to be heated whilst the boiler temp is 1.5 degrees (user setting) higher than TS or until TS temp at coil reaches max temp set by user (but I have this set at 85 so it never reaches this).

• When the TS is up to temp I chuck on 2 or 3x15kg+ logs and the boiler simply tops up the TS as it is depleted for hours – the boiler goes into standby when it has not been able to heat the TS for 30 (user setting) mins.

I do have a flue temp sensor but this is not connected to the boiler controller. 40kW boiler cost E4.5k; 2000 ltr tank-in-tank TS cost E2.3k; 10m2 of FPs cost E2.4k; all the controls, filters, Pumpsx3, TMVs (CH and DHW), PRVs, Exp Vessels cost another E6.3k. Plus 25m of solar pipe and E2k of copper, brass, gate valves, NRVs etc. E300 only for labour (solar commissioning) as DIY.

Posted By: ScotchHi CWatters,
The boiler starts "in the first place" by me manually when I'm lighting it.
The flue thermostat controls the laddomat pump not the boiler, hence the unburnt wood.

I can't decide if this is a simple electrical issue or something more fundamental with the way the boiler works..

It sounds like you just need a simple change to the electrics so that the flue cooling switches off the pump but doesn't prevent it all restarting when the store goes cold. This sort of thing is easily done with a relay costing a few £.

But does the boiler have the capability to relight and feed it self like a pellet boiler? If not how would the control circuit know there is unburnt wood in there (smouldering away?)? Presumably it could try and turn up the boiler and if it didn't detect the flue temperature rising it could shut down until you feed it? That's slightly harder but perhaps not impossible - might need a timer.

Then I guess there is the safety issue. Building a gadget that can automatically relight fires without you being isn't something you do without some thought.

Hi CWatters,
If not how would the control circuit know there is unburnt wood in there (smouldering away?)?
Because if there is wood smouldering the temperature of the boiler is still high. As said above when I find the wood smouldering in the boiler and the accumulator cooling, I activated the flue thermostat manually which starts the laddomat pump, which pumps cool water into the boiler and causes the boiler to come up.

Hi owlman,
The laddomat is connect to the boiler via the flue thermostat only.

PS I have a vigas 25s with laddomat and Akvaterm 1500l accumulator

Hi Scotch,
Just a thought, and I can't speak for the vigas 25, but certainly on my machine and also on others I've seen there is a terminal block allowing the laddomat to be connected, this means the laddomat loading valve and the boiler fans are all controlled via the internal wiring within the boiler. In my particular case this connection is via a plug and socket arrangement, allowing easy disconnection. Others, I believe the Atmos for one are hard wired. It seems to me that in your case the two items, boiler and laddomat are working independently, surely they need to "talk to each other"

Mike

Yes Scotch, my machine has a Lambda flue gas sensor and a temp sensor. I realise that in mine these are all built in, but it just seemed strange to me that there is no form of wiring between the loading valve and the boiler. I presume that you have to manually and independently switch the loading valve on with each burn. Instead of it being switched on automatically when you switch on the boiler. What controls you boiler
fan(s).

Hi Scotch,
It's difficult without seeing the beast, but I can't help feeling the thing is wired up wrong. My gut feeling is that the flue stat and the loading valve should each be wired into the control box/panel of the boiler. Otherwise if the boiler doesn't know what the fluegas temp is how can you get an accurate display readout. Is there a terminal block on the rear of the display panel that allows provision for other add-ons such as a flue fan. Have you been in touch with Solarbayer?

Mike