Either you are not producing enough heat for the demand or the heat you are producing is not getting to the thermal store(TS)

Whilst the spec is for 6.5kW to water this will only be produced when the stove is at full chat with good fuel. So to get 6.5kW into the TS the stove will also have to be outputting 4.6kW to the room. (Manufactures measure output under ideal conditions)

Are you running the stove flat out to get the TS hot - or does (would) this make the room too hot?

Is the wood 2 year seasoned? Otherwise do you know the moisture content.

The laddomat has a circulating pump within to either recirculate the stove or proportionally direct some water to the TS as appropriate. Is this pump running? If yes then is there a speed setting (mine has one) and is it set to max?

The laddomat is looking to adjust the return water to about 60 deg. by mixing flow and return water. If the flow temp never gets up to 60+ then you will never get any flow to the TS. Do you have a temp gauge on the flow?

Do you have a pump on the radiator circuit? If this is running then it might be starving the flow to the TS

Test the temp of the flow and return pipes for both the TS and the rads. Use an ir thermometer or very carefully do it by hand. This should give an indication of what heat you have in the pipes and were it is going.

Do you have a diagram of the system and who installed it?

Thanks for the help guys.

I’m running the stove as hot as I can get it using very dry chopped up pallets and leaving it with coal over night until I return to continue work the following day (hopefully I’ll finish fit out very soon as I have a crane booked for the 12th January to lower me in, this will be my permanent home).
The Laddomat pump is running and on speed 3 the fastest.
Radiator circuit is only 1 gravity fed item and installed as a safety heat sink if the pump fails, I’m told.
The TS has 2 coils in it one for DHW at the top and the heating at the bottom, the boat has underfloor heating but I have all the valves closed to eliminate that being part of the problem.
Flow and return pipes are how but by the time it gets to the Laddomat the thermometers on it are reading around 45/50 so the valve isn’t opening so I’ve removed the valve to test a theory and push what hot water is coming to the Laddomat through into the TS.
I’ve had 50 degrees showing in the top tank stat (there a four stats evenly spread up the tank length).
I’ll ask the plumber ( who is a very good friend of mine and been a gas safe etc etc plumber for 40 years but has never installed a Laddomet before but did his research/asked the suppliers tech team about it. He also as next to no experience of wood burning stoves but again did his homework prior to starting the install.
I’m back there today so can take some pictures if that would help.

Thanks again for the input
Pete

Im not sure how much heat scraps of pallet will produce... lots of flame but I think its a bed of glowing embers/logs that produce heat. If theres little heat going to the TS, the heat leak rad is 1.25 kw and the fire is running hot, the back boiler should be boiling as theres 5kw of heat with no where to go!

The heat leak rad should be so hot you woulnt want to even try touching it! Is it near boiling temperature?

If youve not got one Id buy an IR thermometer and get a stove thermometer so you can see the temps everything is working at.

The stove has 4 x 28mm outlets from boiler and the manufactures recommend diagonal connections for pumped and gravity which is how it’s been installed so the gravity radiator circuit is connected top left and bottom right on boiler, has approx 5 metres of copper pipe to the rad which is 10% of the TS capability and that’s it for that circuit.

https://www.charnwood.com/all-stoves/boiler-stoves/cove/cove-2b/

Buz,

as PinH describes, you need to analyse what's happening, by measuring the system temps, but here are a few things to consider (I've design a good few log boiler stove & TS set-ups). Apologies if this is basic stuff which is obvious;

- the boiler works by lifting the water from the TS by let's say 5oC, and returning to the TS. So if you only draw 20oC water from the base of the TS, you'll never get 60oC water at the top of the TS.
- the laddomat should control what is being returned to the stove, by only letting water pass to the TS, once it is above a set temp (I personally would go for 50oC rather than over 60oC). Until it reaches that set temp, the water from the stove is returned to the stove, in a small circulation loop, so it gets lifted by the 5oC each time it passes GO.
- the point of this is to always supply hottish water to the stove, rather than cold.
- after a little while of re-circing, it will get up to the laddomat set point, let's say 50oC, and allow some to pass to the TS, and of course some cool will draw from the base of the TS, but only in volumes that maintains the blending temp of the set 50oC.
- that will manifest itself, initialy, by the top of the TS getting hot, 50oC+, but the rest of the TS will stay cool.
- eventually, the hot water volume will increase, lowering through the TS, until the base temp rises. Once the base temp rises, then the laddomat's blending valve, will allow larger quantities of water from the TS to go to the stove, with less re-circulation.
- that's when you start to see the TS heating speed up. That is also when you start to see the top of the TS temp increase above the laddomat set temp, since the stove will be receiving ever increasingly hot supply water to it, and thus ever increasingly hot water fed from it.
- the laddomat presumably has two temps to set. One brings on the circ pump, the other is the blending temp. I would suggest you may need to lower the "pump on" temp, say down to 40oC or perhaps less, so that you get circulation (I understood the water is not getting warm at the laddomat location, which may be a bit too far from the stove?)
- that will do no harm, but simply let the laddomat see the warmed water from the stove, which will quite quickly get hotter, until the laddomat blend temp starts to pass a small amount (as described above).
- I personally don't like Laddomats, as running a pump based on a fixed temp isn't very logical. My preferred route is a differential controller (plus TMV), so the pump runs when the stove is hotter than the TS, irrespective of temp.

So, what does all that waffle tell you?? Well, I think you have one issue, that in trying to resolve, you have caused more.

The first issue sounds like the laddomat isn't bringing the circ pump on (soon enough), which may be due to the laddomat being too far from the stove, so the gravity feed (or conduction) can't get it there to start the process. That may be overcome by reducing that "pump on" set point (or adding a remote sensor at the stove).

I suspect by removing the laddomat (if I understood you correctly to have done that?), all you're doing is feeding cold TS water to the stove, so it will take a very much longer time to ever generate a hot output (as above, the stove only lifts the water in-out by say 5oC). That gives that impression that the stove is doing nothing.

The fact that you are not getting high temps at the top of the TS, is more a function of the stove not being fed with hot water (as it should be) rather than insufficient heat at the stove. That is likely due to the laddomat, not being able to do its job (certainly not now that it's being bypassed).

Do your measurements, and you'll see if any of the above is relevant.

I spent all day yesterday on the boat working on it but also trying to get my head around the problem with the heat.

I haven’t removed the Laddomat just removed the mechanical thermostat which didn’t seem to make any difference.

The blending temperature is set using a small thermal probe insert (when up to temperature the prong extends and must push a valve to allow the water to move across to start warming the TS I think). The insert is a 57 degrees unit which I cannot adjust, I think this is the lowest temperature model they make.
The UFH is fed from the TS I’ve just turned the valves off for testing purposes so the TS isn’t trying to heat all the UFH as well, is the a sensible shout?

I’ve removed all controllers so I can switch pumps manually and hopefully find the issue easier. Yesterday I fire up the stove and fed it for approx half an hour, the pipe work at rear (where the is a pipe stat which is isolated at the moment) got too hot to touch so I switch on the Laddomat circulation pump and could feel the hot water make its way the the Laddomat and the circulate back to the stove, I continued to feed the stove during the day but the temperature definitely reduced in the pipe work at rear of stove. The Laddomat has three gauge, one at each pipe location, the stove flow and return was hovering around 50 which isn’t enough to open the valve and allow blending to commence (the Laddomat is over 6 metres from the stove) and I ran out of high calorie wood and was loading stove with smokeless coal which didn’t help or so it appeared.
The feed pipe to the Laddomet has a tee off of it (before the LM) right next to the TS which feeds the DHW section of the TS, this must be what’s warming the top of the TS because the pipe out of the LM going to the TS never got hot all day so the valve obviously didn’t open :(
I’m back again today and will try to find some good wood en route to use and get the stove as hot as possible, my suspicions are the Laddomat it too far away from the stove at 6+ metres and the stove isn’t hot enough even though I would burn my hand easily if I touched the top of it.

Im not convinced your stove is getting up to temperature to power the heat leak rad and the TS. You really need a stove thermometer to know if its up to temp. Not being able to touch the outside of the stove isnt really a good indication. Quite soon after we light our stove you cant touch the outside but the airwash thermometer is barely registering and it takes maybe an hour before the airwash air is up to temp.

A simple check you can do to prove the stove is able to power the TS is as follows. Remove the blending stat/valve as youve already done. Close the top inlet to the laddomat so no hot water can be drawn in. Switch on the pump which should circulate the TS water through the laddomat, through the stove and into the top of the TS. With 6+ metres of 22mm pipe there shouldnt be any problem getting heat from the boiler to the store, if enough heat is available. Maybe pop some pipe insulation over the steaight easy to access sections.

With a blazing fire the stove and TS will start to warm up. How quick that happens depends on the TS capacity. If things dont start to warm fairly quickly, with the stove up to temp, then close off the heat leak rad so that all heat has to go to the TS. If theres no valves on the heat leak rad then wrap it in a sleeping bag/quilt. Make sure you dont isolate any expansion tank!

Posted By: BuzThe feed pipe to the Laddomet has a tee off of it (before the LM) right next to the TS which feeds the DHW section of the TS, this must be what’s warming the top of the TS because the pipe out of the LM going to the TS never got hot all day so the valve obviously didn’t open :(

I'm concerned about the plumbing of the system. The laddomat should not have anything teed off between it and the stove.
As I understand the equipment you have is that the TS has 2 coils within, one for DHW at the top and one for the UFH at the bottom. This si from what you say and a diagram from the website of the TS.
This being the case
The job of the stove is to heat the TS (and to provide heat to the space in which the stove sits)
The job of the TS is to store heat for the DHW and the UFH
The job of the laddomat is to maintain the temp. of the stove back boiler above 60deg.
The stove should not have a direct connection to either the DHW or UFH circuits.

The laddomat should be installed as close as possible to the stove and there should be nothing between the laddomat and the stove. The laddomat should run all the time the stove is lit. The pump in the laddomat will maintain the stove temp. and circulate spare heat to the TS. It is more important to maintain the stove temp than to put heat into the TS and this is what the laddomat will do.

The inclusion of a gravity heat sink rad. also on the stove as an independent connection to the stove will cause delays to heating the TS and will also make the job of the laddomat maintaining the stove temp. difficult. The laddomat has a valve at the base that opens to allow though flow when the unit is not running e.g. in a power cut situation so if the flow to the TS is (can be) constructed to provide gravity flow then I am not convinced that a heat sink rad. is needed as the TS will provide this function
Perhaps take advice from laddomat to see if a gravity circuit supplied by the laddomat valve would be acceptable and I'm not sure if your local plumbing regs would also allow this.

(If you think about the heat sink rad. at 10% of stove output, what happens if the power cut or pump failure occurs when to stove is at say 50% output or more - 10% dump will not do too much to prevent boiling). And at point that I would add is that once you get the system running properly you will have to take care to monitor the temp. of the TS and when the TS temp gets to max you will have to stop feeding the stove regardless of the space temp requirements of where the stove is located.

Buz - a diagram of the system as installed is needed. If possible with pipe lengths and relative heights included.

You mentioned the following;

The feed pipe to the Laddomat has a tee off of it (before the LM) right next to the TS which feeds the DHW section of the TS, this must be what’s warming the top of the TS because the pipe out of the LM going to the TS never got hot all day so the valve obviously didn’t open :(

The flow from the WBS should only go to the top of the TS and tee off to the top port of the Laddomat.
The top DHW coil should be heated indirectly by the primary water in the TS.
The bottom coil is usually used as a preheat DHW coil or a solar coil.
The primary water in the TS should heat your UFH directly.
There should be a connection at the bottom of the thermal store back via the left and right hand bottom ports of the Laddomat 21-60 back to the WBS.
That is how it is usually connected.
Is it possible to shut the water off from the tee going to the top DHW coil to see the effect on the primary water in the TS perhaps?

Thanks guys for taking the trouble to help, I’ve forwarded the thread link to the plumber who is going to the boat tomorrow to move the Laddomat right next door to the stove and remediate any pipe work that requires it. 👍

There are two coils in the tank, upper most for DHW and low for UFH. Both are fed with clean water (as the coils are stainless steel) and the dirty water with inhibitors only passes through the back boiler and the TS main camber.

Way to late on the scene but was this ever resolved. Personally I am with Peter in Hungary with the solution. Just ditch the heat sink rad and use the TS as the heat sink the Laddomat has the built in safety system which copes with any power cut.