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    • CommentAuthorBuz
    • CommentTimeDec 27th 2021
    Hi All,

    I’ve recently had a Cordivari Combi Eco 2 thermal store installed which is fed from a Charnwood Cove 2B wood burning back boiler stove and so far not impressed.
    The problem is the store just isn’t getting up to more than 40 degrees (output quote from manufacturer as wood room 4.6 boiler 6.5, anthracite room 7.1 boiler 9.3) there is a Laddomat 21-60 three way valve which recirculates the boiler water until it reaches 53 or 63 degrees (depending on which thermostat valve is installed) and then opens to allow hot water to fill the tank but I can’t get the valve to open as temperature is too low. The boiler to tank pipes are 22mm and approx 8 metres and the heat dump radiator is fed in 28mm and approx 5 metres from boiler, rad is is per recommendation on data sheet.
    Do you think the boiler is man enough to supply the tank volume and the issue is elsewhere or am not generating enough heat from boiler, at the moment only burning wood but delivery of anthracite coming soon for me to test. I have had it running for approx 5/6 hours a day and 3 days straight.

    Thanks in advance for any wisdom shared :bigsmile:

    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?
    • CommentAuthorphiledge
    • CommentTimeDec 27th 2021
    As above, could do with a few more details on how the system is plumbed. With a wood burner on the floor of the boat and a fairly large gravity fed radiator 5 metres away that would likely put the rad at window height with an expansion tank above that level. Is that how it is?

    With 6.5 kw full boiler output and a 1.25kw heat leak rad, theres up to 5kw going AWOL somewhere which should be fairly easy to track down??

    One thing to consider, and this may not apply to you, the only firewood Ive ever noticed on passing barges is branches scavenged from the side of the canal which are likely fairly wet. Ive never seen a barge with a covered wood store holding seasoned dry logs. Might be worth checking the moisture content of what youre burning??
    • CommentAuthorBuz
    • CommentTimeDec 28th 2021
    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

    • CommentAuthorArtiglio
    • CommentTimeDec 28th 2021
    Do you have a flue thermometer ? If so what’s it showing? Do a burn using wood that’s split to small section (nothing bigger in x section than 1”x1”). Get it going open the airflow into stove as much as possible and keep feeding it and burn as hard and fast as possible, keeping an eye on the flue thermometer to ensure you don’t overheat. Should take less than half hour to get boiler upto temp and laddomat to function, then you can see how temps vary as tank etc heats up and how long it takes to heat up, or see whats not working.
    Often Wood stoves people buy are too big for their needs and get run cooler to prevent overheating in the room, which obviously messes up boiler output.
    • CommentAuthorphiledge
    • CommentTimeDec 28th 2021
    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.
    Posted By: philedgeIf 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 temps at the stove are more important than temps at the TS (to see what is happening)

    You should get about 4kWh/kg of fire wood that is dry to 18% moisture (and half that if fresh) It doesn't make much difference if it is either soft or hard wood - you just need more volume to get a kg. of soft wood. If the pallet wood has been stored under cover it will be about as dry as it gets so you could work out how much heat the stove is producing by noting how much wood you use. It gives a rough idea but all the losses have to be accounted e.g. up the chimney (the sales brochure will give efficiency based on ideal conditions - difficult to get in real life).

    For heat to the TS - you will lose about 0.5kW from stove to the TS (assuming the pipe is not insulated) and less loss on the return (because the temp is closer to ambient).

    You will need to measure the temperatures at the stove
    The flow pipe temp. at the stove output
    The flow pipe temp. to the TS just after the tee to gravity rad
    The flow pipe temp. to the gravity rad. just after the tee to the TS
    The flow pipe at the TS
    The return temp. at the TS
    The top and bottom of the recirculation pipe (stove output to top of laddomat)
    The return temp. between the laddomat and stove
    The return temp. from the TS at the stove
    The return temp. from the gravity rad. at the stove

    If you can get these temps. then it should be possible to see what heat is produced and where it is going.
    • CommentAuthorBuz
    • CommentTimeDec 29th 2021
    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.

    Posted By: BuzThe 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.

    So the heat sink rad and the TS utilise independent flow and return. None the less IMO you still need to measure the temps. of the flow and return at the stove for both the TS and the gravity rad and measure the flow and return temps at the TS along with the temps associated with the Laddomat as above.
    Without the temp measurements it will not be possible to see what heat is produced and where it is going.
    • CommentAuthorGreenPaddy
    • CommentTimeDec 29th 2021

    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.
    • CommentAuthorGareth J
    • CommentTimeDec 29th 2021
    From your first post it sounds like you already know your probably you "can't get the valve to open as the temperature is too low"

    So you need to increase the temperature in your back boiler to allow it to properly get up to temp, open the valve and heat the tank.

    I'd try reducing the pump speed to minimum (there might be a bit or circulation even when the valve is shut), temporarily shut the heat leak rad (ONLY while you're there and monitoring) and firing it as hot and hard as possible.

    If the temperature outlet of the back boiler is suddenly hotter than desired (80+C) up the pump speed or reduce the fire ferocity or both. If that gets you to a steady state situation where hot water is going to the TS and the fire is comfortable, introduce the heat leak rad and see how that alters things.

    Only other thing that seems a bit odd is that you aren't using TS water direct in the UFH. Is that to eliminate risk of sludge in UFH from back boiler?
    • CommentAuthorBuz
    • CommentTimeDec 30th 2021
    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.
    The laddomat pump should run all the time the stove is alight and be switched off when the stove has run out of fuel. A flue thermostat can help / automate this requirement. When the Laddomat pump is not running a valve in the bottom of the unit opens to allow uncontrolled (gravity) circulation, a feature to aid safety in the event of a power cut.

    The main purpose of the Laddomat is to prevent over cooling (= creosote and pollution issues) of the stove when running a pumped system. On a gravity only systems the Laddomat is not needed as the circulation slows as the stove temp. drops so is self regulating (assuming a properly designed system).

    The pump in the Laddomat also pumps the circuit in which the unit is fitted, (and there should not be another pump in the circuit) in this case it will pump to the TS any surplus heat not needed to maintain the stove at a good operating temperature which is governed by the (changeable) thermostat cartridge in the unit. The temp options are 63, 72, 78 and 83 deg. (I run my boiler with the 72 deg cartridge). In operation with my boiler the temp of the boiler rises to 72 deg without any heat going to the TS, once the boiler is up to 72 deg. the surplus heat goes to the TS by virtue of the fact that the mixing valve maintains the input temp at 72 deg. Generally speaking a boiler will only lift the temp. by about 20 deg.

    In the system under discussion the Laddomat should be in the circuit to the TS and should be located close to the stove and at the same level as the stove return connection. The 3 temp. gauges on the Laddomat are useful to show the return temp., the stove input temp. and the stove recirculation temp. In addition to these temps. it would be useful to know the other temps (listed above) to determine what is happening.

    Buz - as a first pass it would be useful to know what these temps. are if you don't have a suitable thermometer to record all the temps. The temps. should be noted at various times during the heating cycle.

    The Laddomat pump may interfere with the operation of the gravity heat sink rad. as combination pumped and gravity systems can produce unpredictable results due to pump pressures set up.

    Cross-posted with Buz
    The Laddomat is too far away from the stove.
    There should be no tee off between the stove and the Laddomat.
    Do you have a diagram of the system you can post here?

    This in addition to the points above
    • CommentAuthorphiledge
    • CommentTimeDec 30th 2021
    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!
    • CommentAuthorGareth J
    • CommentTimeDec 30th 2021
    What informed the decision to use a 57C valve? I would expect a boiler to operate better at a hotter temp. But don't know the specifics of your fire, maybe that's the recommended temp?

    If it's opening too soon, you could be cooling the firebox down too much and resulting in a fire that struggles to get up to and stay at efficient operating temps.
    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.
    • CommentAuthorphiledge
    • CommentTimeDec 31st 2021
    Probably need to consider Charnwoods install guidance for details of what the stove needs and probably what needs to be included in the system. The heat leak rad needs to be minimum of 1.25kw which is significantly more than 10% of boiler output. The heat leak circuit needs to be unvalved so probably best not to use the laddomat for a safety heat dump.

    Charnwood recommend 45degC minimum return temp to the boiler so the laddomats documented minimum return temp of 63degC(57???) is higher than it need be and will delay charging the TS a bit.

    I think there will be a T piece before the laddomat as the hot flow from the stove has to route to both the laddomat and the top of the TS........ assuming thats where to pipework has been run to!!!!
    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?
    • CommentAuthorowlman
    • CommentTimeJan 3rd 2022 edited
    Posted By: winterbourne.
    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?

    The layout between the heat source and the tank as you describe, is broadly similar to the layout on most logwood gasification boilers linked to large accumulator tanks.
    When the boiler is switched on and fans etc are activated the laddomat "motorised loading valve" is also activated and water from the stove is "short circuited" in a loop; boiler to laddomat, and back to the boiler until the critical temp is reached when the wax thermostatic devices progressively open.
    At that point they allow some water from bottom of the tank to enter the stove therefore allowing some warm water to enter the top of the tank via the T piece you mention. This automatic and progressive opening one port and closing of another is the function of this loading valve.
    If your primary water is also Teed. off to the DHW coil water is sucked from there too as the laddomat operates.

    Heated water delivered from that simple boiler/tank set up, to other uses e.g. CH, DHW or Plate heat exchanger, is either pumped, or in your case, via a coil and should be independent of the boiler/store set up.

    I'm with Peter in Hungary, I think you set up may be suspect. Both of us operate log gas boilers.
    • CommentAuthorBuz
    • CommentTimeJan 3rd 2022
    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. 👍
    • CommentAuthorowlman
    • CommentTimeJan 3rd 2022
    Peter; just as an afterthought, does water from your DHW coil go direct to the taps etc.. Or does that coil go to some sort of heat exchange HW storage facility?
    If it's the former, and if I understand your description correctly then the "Dirty" water in the stove, the store and connecting pipework, is being supplied direct to the taps. The store is meant to keep the two separate.

    P.S. I haven't read all this thread, so apologies if someone has mentioned this before and you are already aware.
    • CommentAuthorBuz
    • CommentTimeJan 4th 2022
    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.
    Perhaps before the plumber starts ripping apart the system get a plan as to what to do that will give what you need from your system. E.G.is it acceptable to use the TS as the heat sink rad? (my system does). If you can use the TS as the heat sink and do away with the gravity rad. then you will have more control over the heating and quicker heating of the TS therefore quicker recovery of the DHW.

    Can you move the TS closer to the stove (Laddomat installation talks about 6m max between stove and TS using 32mm pipe. My Laddomat is fitted immediately behind the boiler)

    No mention yet of DHW outside the heating season.

    A diagram with lengths and heights/levels would be useful

    Do you have and has the plumber read the Laddomat installation guide
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