injector tee and bad flow to cylinder

[monk2601]

i have recently installed a stanley solid fuel stove, i have the flow and return connected to the cylinder by a gravity circuit and the rads are pumped,however whenever the pump comes on the the flow to the cylinder does not heat,i fitted an injector tee as specified by the manufacturers instructions and this was meant to prevent this happening,any ideas on why thecylinder flow is not heating properly

 

[Tibbot]

Have you installed the injector tee on the return with separate flows to CH & HW?

 

[Norcon]

Are you acheiving gravity flow to the cylinder?

 

[monk2601]

i have 2 direct flow and returns coming from my stove [1 flow and 1 return] to the hot press by gravity circuit.i took a tee off the flow in the hot press and connected to my rads.where my gravity return comes out of the cylinder this is where the injector tee is with my rad return connected to it,the pump is situated on the rad return just before where it connects to the injector tee. i have the expansion pipe tee,d off the flow at the cylinder and i have the cold feed connected into the expansion pipe,i wonder would the pressure of the cold feed prevent the clyinder flow from circulating whenever the pump is on

 

[JohnD]

the pump will try to suck all the hot into the rads.

 

[Norcon]

i have the expansion pipe tee,d off the flow at the cylinder and i have the cold feed connected into the expansion pipe,

The vent pipe should rise to the cold feed & expansion tank.
The cold feed should be connected on the return side of the cooling set up, whether that is a hot water cylinder, thermal store, radiator, cooling coil, plate cooler or some other method.
So in an over heat situation a safe circuit is acheived keeping the boiler cooled.

Your first priority is to ensure the gravity circuit is thermo syphoning without any pumps operating. Thats quite easy to do by just feeling the pipes.
What size pipes have you used? Have you ensured a rising gradient on the flow and a falling gradient on the return?
Have you used a pipe bender to make direction changes?
Up too 6m horizontal with a 0.8% gradient will work with 28mm pipes!
Will your pipework configuration allow air to escape without pockets?

A hi-Lo stat set up should be used.
If you only fit a flow stat, cold water from the heating circuit will be dumped back into boiler return creating condensation and cold flue problems leading to early boiler failure and will also cool the hot water in the cylinder!

i wonder would the pressure of the cold feed prevent the clyinder flow from circulating

No

 

[monk2601]

i have 28mm pipes coming from my stove and connecting to my cylinder, i tee,d off these pipes in 22mm to connect to my rads. i have the flow rising from the stove to the cylinder and the return is falling back to the stove,the gravity circuit is working perfectly when the pump is off its only when the pump is on that the gravity circuit to the cylinder wont work.i just have an ordinary pipe stat fitted,ie,when the water reaches a set temp it calls on the pump and when the water cools below that same set temp the pump turns off,is this a high-low stat.the make of the stat is IMIT BRC if that can tell you anything.thanks much appreciated

 

[Norcon]

is this a high-low stat

No.
With a hi-lo stat configuration you have two stats wired in series.
One on the flow and one on the return. So two switching devices to turn the pump on and off.

Its more important that the return stat energises the pump as at this stage hot water will have reached the cylinder through thermosyphoning.
When the pump operates then the injector T should be doing its job of accelerating flow through the cylinder.

 

[monkplumber]

so would the stat on the return turn on the pump and then the stat on the flow turn it off,eg,return reaches 60 and pump comes on and flow reaches 40 and pump turns off.would you just use 2 ordinary pipe stats and if so how would you wire it. when the pump operates is it not the job of the injector tee that the pumped ch does not prevent the gravity circuit from working which is currently happening on my system,as soon as the pump comes on the cylinder does not heat by thermosyphoning,cheers thanks for the help

 

[Norcon]

Page 17 you'll find a wiring diagram.
http://www.woodwarmstoves.co.uk/_assets/manuals/new instructions fireview march 2010.pdf

What stove do you have? A Stanley erin by any chance?
An injector T is a flow accelerator device driven by the venturi effect.
You do have a manufactured one with the nicely tapered jet?
And is it installed correctly?

 

[monk2601]

its a stanley lismore,no i made the injector using a 28 mm to 15 mm solder reducer pushed into a 28mm tee,i looked them up online and it was recommended to make one up like that because they were hard to come by and fairly expensive,well ill go and get a proper injector tee and try that to see if that works and ill let you know how i get on,it must be that because everything else is plumbed right to stanley,s instructions and even stanley state to just use 1 stat on the flow and to set it to 55 degrees,cheers

 

[DeltaT2]

its a stanley lismore,no i made the injector using a 28 mm to 15 mm solder reducer pushed into a 28mm tee,i looked them up online and it was recommended to make one up like that because they were hard to come by and fairly expensive,well ill go and get a proper injector tee and try that to see if that works and ill let you know how i get on,it must be that because everything else is plumbed right to stanley,s instructions and even stanley state to just use 1 stat on the flow and to set it to 55 degrees,cheers

I wouldn't worry too much about the injector tee mate, if you've copied the standard injection tee, then it'll be OK. We make up our own inj. tees.

Post up a rough detail showing your layout/connection etc. By the way, have a good look at the Woodwarm installation details, they're 100 times better than Stanley's.
HTH

 

[Norcon]

I don't see 55c mentioned in the lismores MI's. They do mention maintaining the return above 40c though!

Woodwarms set up will give much greater priority to the cylinder and won't rob it off heat once heated.
You can apply the same arrangement to the lismore.

If your starting up the pump @55c on the flow on a big load of cold rads then its quite likely a cold glug is being transferred through the cylinder circuit.
My local supplier sells injector T's by the dozen.

 

[monkplumber]

well i,ve finally think i,ve solved my injector tee problem,i had the pump turned down to its lowest speed setting,i,ve since turned it up to the middle speed and the gravity circuit seems to be working now when the pump is on, the higher velocity of the water coming through the venturi must be creating more negative pressure on the return and thus helping it flow better, thanks for all the advice lads now just to wire these stats

 

[DeltaT2]

I prefer to Cross Flow the boiler & you're always best to use the High & Low pipe thermostats & forget a timeswitch/programmer controlling the circulation pump.

The Honeywell pipe stats are cheaper & better than Danfoss AT stats.