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Heating and cooling: multifuel thermal store problem

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    • CommentAuthorMaddy
    • CommentTimeNov 28th 2014
     
    I'm afraid neither my husband or I would understand a technical reply. We are pensioners but first time buyers so have no experience of DIY. We have a multifuel logburner that we wanted as a prime source of heat. We have had the stove since september and been using it running on oil till the elctrician and plumber could spare the time to come back and set up the stove to connect to the Gledhill Torrent GreenHeat OV Thermal Store Cylinders118934 1449 x 530 170 and Worcester Danesmoor Utility 18/25 oil system boiler, the multifuel log burner Stove is Nero Lux BC . I think they delayed because they found it too complicated. But now they haveset it up, we light the fire and the oil boiler kicks in too from time to time. I can't find any operating instructions for a layman and Greenheat don't have any as they say it varies from plumber to plumber. reading this forum i fear it is set up wrongly as there is a programmer that should have been put on the boiler but they just replaced the one on the wall. They won't come back as they are too busy before Xmas and argue that we are warm enough when others have no heat. True enough, but we are worried about overheating and using double the amount of fuel. My question is,How can we prioritise the wood burner and prevent the oil from running at the same time, is it the thermostats ?
    What should they be set on?
    we have one next to thermal store which came with it (cylinder thermostat I think)
    We have 2 we are allowed to operate - the one downstairs Honeywell (about 5cms) we used to operate the oil heating with and the one next to the radiator pump, (which the plumber added) which is at 33C and when the radiators don’t heat up but the fire is roaring I drop the temperature on that and the pump starts. We have to have the pumps as there isn’t enough incline for gravity feed. There is a temperature controller on the greenstar boiler I was told not to touch.
    Is there a way to just switch off the oil boiler until we can get this sorted?
    and dare I ask another heating company to check the work of another or will they just refer me back to our reluctant team? Who could I ask?
  2.  
    That thermal store would seem to be 170 ltrs, which seems tiny for CH and HW - OK for domestic hot water (DHW) only, but likely insufficient capacity to take the output of a lively wood-burner. On the other hand, not sure how 'lively' it will be: http://www.greymetal.co.uk/nero-lux-boiler-grey-535.html. Nominal 6kW to room and 5kW to the boiler - and that's flat out on wood.

    Welcome, by the way, to GBF. You will, I am sure, get much help here. I am not a plumber, but no doubt one will be along in a minute!
    •  
      CommentAuthorSteamyTea
    • CommentTimeNov 28th 2014 edited
     
    Welcome.

    Have you tried running the system on just oil?
    If so, did it seem to work normally?

    Posted By: MaddyWe have 2 we are allowed to operate - the one downstairs Honeywell (about 5cms) we used to operate the oil heating with and the one next to the radiator pump, (which the plumber added) which is at 33C and when the radiators don’t heat up but the fire is roaring I drop the temperature on that and the pump starts.
    This bit confused me, but I think it is working as a manual override for the oil side of things. Why turning it down makes the oil side of it work.
    If there is no gravity feed, and the pump is operated by that switch, then you could try turning off the oil to the oil burner (should be a valve somewhere), get some wood burning and see what happens. There may be an electrical interlock that stops the pump when there is no oil burning, but without seeing a system diagram it is hard to tell.

    My one concert would be that if you have a lot of heat from the wood burner and no pump operating, where is the heat going? Eventually it could boil and cause serious problems.
  4.  
    A lot will depend on the way that things are plumbed, but my mind runs back to a problem a client had with a wood-burning Rayburn/LPG boiler combo. If I remember rightly, the LPG boiler installer had wired the programmer in such a way that it gave priority to the boiler, effectively by controlling output from the boiler, not output (regardless of the fuel used for input) from the TS. In that case (though I think the Rayburn was rated about 15kW - so much more than yours - one of the issues was that the TS was far too small in any case.
    •  
      CommentAuthorSteamyTea
    • CommentTimeNov 28th 2014
     
    TS = Thermal Store (and it does seem a bit small, smaller than my domestic hot water (DHW) cylinder for my small house.

    I would consider asking someone else to look at it. Where in the country are you?
  6.  
    Hi
    The way I expect your system to work is
    The Thermal Store (TS) will supply the heat for the Central Heating (CH) and the Hot Water (DHW) via the heat exchanger attached to the TS
    The TS will be heated by the Oil Boiler (OB) and the Wood Stove (WS) individually or in combination)

    If you do nothing when the TS temperature is low (because you have used heat by CH or DHW use) then the TS will demand heat from the OB and this will automatically start up and run until the TS is hot enough.

    If you light the WS this will supply heat to the TS and if there is enough heat supplied from the WS then the OB will not switch on.

    If you have the WS lit and you are using more heat than is supplied by the WS then the OB will start to make up the short fall. So in some circumstances I would expect the OB will start occasionally when the WS is lit.

    There will be no way to prioritise the WS over the OB other than by keeping the WS lit and producing enough heat to cover the demand

    If you turn off the OB then you may / will run out of CH or DHW when the WS is not lit for an extended period e.g. over night or you go out for the day

    The thermostats I would expect to see controlling the system are
    A thermostat on the TS controlling the heat demand from the OB (if this is set to say 60 deg then the OB will switch on less frequently when the WS is lit than if it is set to a higher temperature, experience will show the lowest acceptable temperature)
    A thermostat controlling the CH (sensing the room temperature) This should not be in the same room as the WS This may be a programmable room thermostat to give timed / temperature control for the CH and is possibly the one added by the plumber.
    A thermostat on the WS to start the WS pump when the WS is up to temperature
    A thermostat on the OB to regulate the heat output of the OB (probably either on or inside the OB)
    If the TS has immersion heater(s) then there will be a thermostat on the TS to control the heating via the immersion (e.g. for summer use when night rate (E7?) electricity might be cheaper than oil for DHW)

    You won't get an instruction manual / users guide for the whole system as it is an individually made up system and time and experience will tell you how to get the best out of it.

    Health warning..Without seeing the system or a diagram it is difficult to be definite about this system from the comfort of my arm chair. In particular it is difficult to define what each thermostat will control without sight of the system. However the above is what I would expect.

    But I hope this helps a bit Sorry about the alphabet spaghetti above but is saves lots of typing!
  7.  
    Nice one, P-in-H!

    A couple of extra background points for Maddy:

    * You will find many threads on here re Thermal Stores (TS) or accumulators. In general these will be very big - probably no smaller than 500-800 ltr, and 2000 ltrs and up is not uncommon. A common set of heat-sources for such an accumulator might be a log ('batch') boiler, solar water heating (SWH), possibly a dump-load (via an immersion htr) from PV (solar elec) and so on. The main point is that the store is BIG, and acts (a) to allow multiple inputs) and (b) - and most importantly - to separate 'burn time' from heating time. Thus (if you had one!) you might light your log batch boiler - a big box like a fridge-freezer into which you stack a big pile of logs - in the morning and then go out for the day. *That does not matter*, because you are storing the heat for future use. When your programmer tells the central heating (CH) to come on at 6 p.m., maybe several hours after the boiler has gone out, that's OK, because your energy to run the CH is stored as heat in the (hopefully very well-insulated) accumulator.

    * Your TS is too small to behave like this, so most of the time (except the very short period while 170 ltrs of stored hot water is exhausted), you have to 'burn' at the same time as you demand heat. If you want to prioritise use of the wood-burner (or rather *not* to use the oil boiler), the only way to be warm when you wake up at 7.00 is to get up at 5.00, light the stove, and go back to bed for a while. Not a sustainable course of action, I feel!

    And re P-in-H's point re 'Alphabetti Spaghetti' I have (after an early lapse) tried to include full 'titles' with abbreviations in brackets so that the abbreviations can subsequently be used and understood.

    Good luck!

    Nick
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    Oh Wow, how generous you all are to help. Thank you. We have been so worried and confused.
    i'll need to try and sift through all this carefully but already things are a little clearer.thanks also for using words and not initials! I'll return with feedback when i've experimented.
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    <blockquote><cite>Posted By: SteamyTea</cite>Welcome.

    Have you tried running the system on just oil?
    YES,
    If so, did it seem to work normally?
    YES

    <blockquote><cite>Posted By: Maddy</cite>We have 2 we are allowed to operate - the one downstairs Honeywell (about 5cms) we used to operate the oil heating with and the one next to the radiator pump, (which the plumber added) which is at 33C and when the radiators don’t heat up but the fire is roaring I drop the temperature on that and the pump starts.</blockquote>This bit confused me, but I think it is working as a manual override for the oil side of things. Why turning it down makes the oil side of it work.
    NO,WHEN I TURN IT DOWN IT MAKES THE PUMP FOR THE RADIATORS WORK.
    If there is no gravity feed, and the pump is operated by that switch, then you could try turning off the oil to the oil burner (should be a valve somewhere), get some wood burning and see what happens.
    I DAREN'T
    There may be an electrical interlock that stops the pump when there is no oil burning, but without seeing a system diagram it is hard to tell.
    I COULD TAKE PHOTOS IF YOU LIKE?

    My one concern would be that if you have a lot of heat from the wood burner and no pump operating, where is the heat going? Eventually it could boil and cause serious problems.</blockquote>
    YES, ME TOO, SO I KEEP RUNNING UPSTAIRS AND CHECKING THAT THE LIGHT IS ON ON THE PUMPS, AND WE HAVE A UPS BATTERY THING IF THERE IS A POWER CUT.
    I JUST CAN'T UNDERSTAND WHY THE OIL KICKS IN AT ALL IF THE STOVE IS PUTTING OUT SO MUCH HEAT SO I'M GOING TO TRY TO ALTER THE THERMOSTAT ON THE TANK (SORRY -TS) AS PETER SUGGESTED, ASSUMING THAT WAS 60C ?
  10.  
    Remiss of me; I have not even asked how big the house is, and to what thermal standards it has been built or improved. If you do not have an idea of the insulatioon standards, the age of the building will give us a clue.
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    Hi Nick, it's 2 bed 2 reception room cottage.Old. 2 foot thick stone walls which we have put thick insulation board on where we had to chip off damp plaster, so not everywhere but more than 50%.
    I tried the temperature alteration on the tank (TS) to 60C And the oil burner stopped burning, ( hurray) so then I opened up another radiator and the oil burner kicked in again ( awh) but not for long
    The thermostat that reacts to the room temperature, when I just checked now, was lower than the 'click' and usually, when we had it running on just oil, the radiators would not work in that position - but now with the wood stove on they ARE hot, so that bodes well
    ( oh , the oil burner has kicked in again briefly ) Should I turn down the temperature on the Oil Burner too? ( My plumber said I wasn't to touch it)
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    I've looked at the ordersheet 'Gledhill torrent greenheat 400L' so I think it's 400 litres Thermal store
  13.  
    Hi Maddy
    A couple of points, when you are quoting a post, if you make sure the Html button is selected then the quoted part comes up in a blue shaded box, just makes it a bit easier to read. Also writing in upper case is usually understood to be SHOUTING!! - just forum etiquette.

    So you have a house with at least a ground and first floor. Do you have a radiator somewhere (probably upstairs)
    that gets warm or hot when the wood stove is on regardless of any other settings?

    I am a bit puzzled as to why you do not have any gravity circulation. Is the thermal store upstairs and the wood stove downstairs? If not how close is the Thermal store to the wood stove

    When you light the wood stove do the pipes from the wood stove to the thermal store start to get warm quite quickly without the pump running?

    A 400l thermal store would make much more sense. The typical calculation for a thermal store would be 50 times (in liters) the capacity of the wood stove. So your 5kw (to water) wood stove should have at least 250l. a 400l store would give some chance of having heat / hot water for the morning (if the night time temperature was set low enough)

    By the way you can turn the oil boiler off by turning of its electricity supply as modern boilers won't run without electricity.
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    oh, Peter, i am sorry, I didn't mean to shout, just separate my comment. I haven't had a chance to see what just the wood stove does to radiators but there is an upstairs bathroom radiator and one in the downstairs hallway that i have to leave on all the time to let the heat escape. I'm not sure if there is no gravity circulation at all, just been told that 'cus of the low ceilings upstairs the header tank can't get enough angle on it, it's virtually level. The Thermal Store is in our bedroom. Thank you for telling me the tip about turning off the electric on the oil burner. If there is no detrimental effect from that i could give it a go to test how the wood burner does on it's own. At the moment there is a reduction in the frequency of the oil burner kicking in which must be due to turning down the temperature on the TS I assume, so thanks for that tip.
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    Hi Peter, where do I set the night time temperature low enough? Is that the room thermostat in the hall?
  16.  
    Posted By: Maddy( oh , the oil burner has kicked in again briefly ) Should I turn down the temperature on the Oil Burner too? ( My plumber said I wasn't to touch it)

    I would expect the thermostat on the oil boiler will govern the output temperature of the boiler. There is probably no advantage to turning this down as the store will be calling for heat from the oil boiler and it will get lower temperature water, which could make the boiler run longer to get the temperature up (and also lower the efficiency of the oil boiler).

    With the oil boiler switching on and off it sounds like the wood stove is only just managing to keep up with the demand. Do you have a temperature gauge on the thermal store - if so what does it say?
  17.  
    Posted By: MaddyHi Peter, where do I set the night time temperature low enough? Is that the room thermostat in the hall?

    It will be the thermostat that senses the room temperature, probably the one in the hall. Is this the programmable type?
  18.  
    Do you have a portable thermometer? It's fine getting the system to be less reliant on oil, but are you getting comfortable temps when you do so?

    Re the TS capacity, see https://www.plumbnation.co.uk/site/gledhill-torrent-greenheat-ov-thermal-store-cylinders/

    The 118934 is listed as 170 litres.
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    programmable thermostat, yes.
    Thermometer for cakes, yes, is htat to measure water temp?
    I switched off the electric supply to oil burner, but the pumps stopped too so it's back on again now
    I have pics if I can load them
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
    and another
    • CommentAuthorMaddy
    • CommentTimeNov 29th 2014
     
  22.  
    400 litre is 0.4 cu metres. That store does not look that big. I was trying to do a calc from the dimensions, the TS itself.but I guess they must include the insulation, so I don't know the actual measurement of the store.

    And I meant the thermometer for checking room temp. Your degree of comfort can do that to some extent, but you can be a bit more 'scientific' if you know the temps of all the elements of te system it helps.
    • CommentAuthorMaddy
    • CommentTimeNov 30th 2014
     
    Sorry, Nick I can't help with the measurement of the Thermal Store.
    my cooking thermometer gives me the room temperature and now the heating has just gone off and the fire died down it is a comfortable 26 degrees. it has been too hot with the fire and the boiler too.I noticed when I didn't draw water in the evening for washing that, even though the fire had dropped, the oil boiler didn't fire up so I see how it works as you explained. I'm getting the picture now.Would it make sense for me to lower the temperature on the Thermal Store some more, below 60 degrees?

    Peter, I don't seem to have a temperature gauge on the thermal store to tell me the internal temperature, that sounds like a good idea, wonder if I can get one? and tomorrow I'll switch off the electric briefly to the oil burner and just light the stove. I am curious to see if the pipes from the wood stove to the thermal store get warm quickly without the pump running.I'll let you know.
  24.  
    Maddy,

    I know our comfort levels all vary, but, for me, 'comfortable' and '26 degrees' would not go together at all! How much hotter was it with the stove on?!

    You refer to 'lower(ing) the temperature on the thermal store' then later you say 'I don't seem to have a temperature gauge on the thermal store'. I guess you are saying that you can *set* the temp, but not *know* the temp.

    You can get very cheap infra red thermometers from Maplin and other similar outlets. They are 'point and shoot', and very useful.

    Nick
    •  
      CommentAuthorSteamyTea
    • CommentTimeNov 30th 2014
     
    Posted By: Nick ParsonsYou can get very cheap infra red thermometers from Maplin and other similar outlets. They are 'point and shoot', and very useful.
    Got mine from Lidl and it is great.
    Wish my house was 26°C, I feel guilty that it is 22° :bigsmile:
    • CommentAuthorEd Davies
    • CommentTimeNov 30th 2014 edited
     
    I'd second the Lidl IR thermometer suggestion: I have three IR thermometers from different suppliers. One has failed [¹], one is not very accurate [²] and the other one's from Lidl:

    http://www.lidl.de/de/powerfix-temperaturscanner-infrarot-ptsi-9-a1/p60602

    Quite a bit larger than the others but takes standard batteries (PP3), has quite a small viewing spot (good) and seems accurate and robust.

    Only difficultly is knowing when they'll have them in stock.

    [Ă‚Âą] From an online electronic component retailer (Rapid Electronics). Expensive (about Ă‚ÂŁ45 IIRC) and worked well for a couple of years but now doesn't start up properly except occasionally and briefly with very fresh batteries. Dunno why - no obvious signs of breakage or water ingress or anything.

    [²] Cheapo (£15) Maplin one which looks like a slightly chubby white pen. Large “viewing cone” and under-reads by quite a few degrees, I think. Also eats batteries fairly rapidly.
    • CommentAuthorMaddy
    • CommentTimeNov 30th 2014
     
    Posted By: Nick Parsons'comfortable' and '26 degrees' would not go together at all!

    Ah, I see I forgot to mention - this was 26 on my cake thermometer, not sure what that is on a real thermometer. I'll clearly have to get one. Thanks for the link, Ed, for the thermometer

    Posted By: Nick ParsonsI guess you are saying that you can *set* the temp, but not *know* the temp.

    Yes
    Progress report, I let the fire die out overnight and measuerd ( if it's to be trusted ) the temperature of the pipes around the TS this morning, where they joined the tank. The Open vent and the DHW senser were the hottest reading 47 and all the others about 15 degrees less. except for the Solid Fuel Return pipe that was cold.
    I lit the woodburner without the power to the oil burner and very quickly ( 3 mins) the open Vent and the Solid Fuel flow got to 52 ( cake degrees) and the solid fuel return was warmish. The pumps weren't working so I put the power back on to the oil burner which seemed to switch the pump on. I thought I'd risk turning down the guage on the Thermal Store a bit more to 55 degrees and that seems to have done the trick. Is it Ok to leave it at that temperature? It's made it a lot more comfortable in the house as I just seemed to have red hot and not warm. If it's safe enough to leave like that then 'I think your work here is done'. You have all been so helpful , informative, generous and above all patient. We are so grateful.
  28.  
    IANAHE (I am not a heating engineer!), but I think you should be fine with a TS temp of 55 degrees. If it were a conventional cylinder, that would be 'stored hot water', and you would want to keep it at 60 degrees for full protection against legionella bacteria, but since (if I understand correctly) your domestic hot water (DHW) is *not* stored, it's coming direct from the (cold) mains via a heat exchanger, so you should be OK. The only issue (if I am correct so far) is whether 55 degree (maximum) TS temp minus heat exchanger losses = warm enough hot water and warm enough radiators leading to warm enough rooms and warm enough people. If it does, with the caveats above, sounds like it should be OK.

    I love the idea of 'cake degrees'!!

    I am so glad it is coming together.

    Nick
    • CommentAuthorMaddy
    • CommentTimeNov 30th 2014
     
    it's definitely warm enough. But you've got me worried again now : )
    I had read about the cold mains for water, but how come the water from the tap was warm this morning before I lit the fire or switched on the boiler?
  30.  
    Dunno! You haven't got an immersion heater turned on, have you?

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