Trouble shooting complex CH problems

[Drain]

Norcon, thanks for the insight which has certainly made me think. Do your comments apply to thermal stores in general or to the Chelmer Thermocat in particular?
I can see what you are driving at but you seem to be assuming that thermal store thermostats do not have any hysteresis. My understanding is that the Thermocat lower (ie UFH) stat can be set to fire the boiler at <=40C and cut it off at >=50C. Assuming about 140L of water in the lower half of the store, and assuming that water has a thermal capacity of 0.001KWH per L per 1C (my 3KW jug kettle takes ~2' to boil 1L of very cold water), then the boiler will deliver 1.4KWH to the store in one cycle. My new Grant Vortex boiler is rated at 23KW so this should take it about 4 minutes. If the UFH or DHW demands hot water at the same time then this period will obviously be extended beyond 4' but I cannot see what might reduce it.
In the case of the Grant boiler it condenses up to 55C according to its spec so with the UFH stat set to cut out at 50C the boiler will never be asked to operate outside its condensing range by the UFH.
Of course the DHW may be another matter but in our case the DHW demands should be relatively minor.
As stated in my previous post we are still some way off finding how it all works out in practice.

 

[Norcon]

Do your comments apply to thermal stores in general or to the Chelmer Thermocat in particular?

To any thermal store/buffer cylinder particulary where the buffer volume is low.
A parallel connection would be better as the charging flow rate will be much lower thus helping to reduce mixing and the volume increased considerably.

The thermocat is nothing more than a vertical low loss header with an increased volume and the capability to supply the dhw from the top section.
Immersed heat exchangers can mean scale build up problems in hard water areas. Once you lose performance you will start upping the top section temperature and exacerbate the problem.

 

[Drain]

Norcon, thanks for reply.

Immersed heat exchangers can mean scale build up problems in hard water areas. Once you lose performance you will start upping the top section temperature and exacerbate the problem.

Thanks for warning. We are indeed in a hard water area and I have just started to look at water treatment plants. I will probably raise the specification of the water softening component as a result of your comment.

Re your criticisms of thermal stores in general I deduce that you are in flat disagreement with this paragraph from
http://www.heatweb.com/techtips/Underfloor/underfloorheating.html

Buffer Store Operation.
The only way to ensure that condensing boilers run continuously in condensing mode for heating, or to overcome nuisance cycling of boilers, is to tie a thermal store into the underfloor system. The store acts as a buffer between the heating load and the boiler output. It saves up heat energy while the boiler is firing, and then uses that stored heat to keep the heating going once the boiler stops firing. This way the boiler does not have to fire so often, and will burn for longer when it does.

Heating is a subject in which even the experts disagree it appears!

 

[Boilerhe1p]

For starters that boilers not bog enough for what your running anyway ... 88degrees running at max is ridiculous your basically running a d or e band boiler as the efficiency is rated at 55-60degrees which is a rated at max you can wave bye bye to that .. Also thats to close to the overheat/limit stat if there is sludge/restrictions on the system which spunds like there is it will constantly o/heat when all the valves close sack the bypass its probly blocked rip it out and drop a gate valve in left open a few turns.. if the waters that colour it suggests air intrainment in other words poor sustem design its dragging air in which doesnt happen much on sealed systems unless theres a weak joint somewhere? Why thermal store?? And not unvented tank on a y/s plan with zones controlled by room stats?? Sounds a bit of a dippy install also if it wasn't cold flushed and hot flushed after install with correct chemical added afterwards the left over flux in the system can start corroding the system/ boiler which is probably what's happening with your heat exchangers! It probably wants flushing a chemical.. If the water quality is poor Worcester will not change the heat exchange on the warrantee provided it was filled on and signed off and still under warrantee??

 

[matt1e]

For starters that boilers not bog enough for what your running anyway ...

For starters you should be reading the dates on the posts you are going to comment on

this one is more than three years old mate

Matt

 

[picasso]

He seems to be on some kinda saunier duval trip, maybe the medication too strong or its wearing off, difficult to tell.

 

[matt1e]

Aye so I see picasso


Matt

 

[Agile]

Even allowing for being from Wolverhampton, his spelling and grammar make it very difficult to understand what he is trying to say!

 

[sooey]

As soon as a mod sees the rubbish you're spouting you'll be banned. Bye & good riddance.

 

[matt1e]

Aye so I see picasso


Matt

Have you even ever had a job?? I mean it's a bit of a s**t tip up there pal and for the scraps of work that are around I possibly wouldn't be looking to give to a gobby little c**t like you :-/ I'd rather give the work to the polish and watch you inject heroin because your life sucks so bad

For starters that boilers not bog enough for what your running anyway ...

For starters you should be reading the dates on the posts you are going to comment on

this one is more than three years old mate

Matt

That may be cock features it half of these are really unresolved and people looking with the same issues won't no what to do so go dig a hole and lie in it you gimp... jealousy as you have no knowledge of anything so you try to mock people that do maybe you should go back to school???

Got a job ta,and a one you would be hopelessly out of your depth with too
you also seem to think my reply was aimed at belittling you, if you cant tell the difference between light hearted banter and insults then you shouldn't be posting on a forum
you need to grow up son instead of acting like a 12 year old spoilt brat of a girl
Although you do also seem to enjoy talking about cock somewhat so tell me
Are you a girl?


Matt

 

[Agile]

As soon as a mod sees the rubbish you're spouting you'll be banned. Bye & good riddance.

Done!

Thanks

 

[Onetap]

Re your criticisms of thermal stores in general I deduce that you are in flat disagreement with this paragraph from
http://www.heatweb.com/techtips/Underfloor/underfloorheating.html

Buffer Store Operation.
The only way to ensure that condensing boilers run continuously in condensing mode for heating, or to overcome nuisance cycling of boilers, is to tie a thermal store into the underfloor system. The store acts as a buffer between the heating load and the boiler output. It saves up heat energy while the boiler is firing, and then uses that stored heat to keep the heating going once the boiler stops firing. This way the boiler does not have to fire so often, and will burn for longer when it does.

Heating is a subject in which even the experts disagree it appears!

3+ years old, but I fee compelled to note the the advice above is on the website of a company that sells heat banks/thermal stores.