help, Stove back boiler boiling the water!!!

NewBeefFarmer

Hi,

new stove. with back boiler.

stove is correct output for heating water only, in case ur wondering that im using the wrong stove and too much kw is going to tank.

only heating water only. 300ltr tank in hotpress

thing is, the gravity system was just possible. i remember this as the plumper told me, after i told him the height of stove.
when we light the stove, all is grand for an hr or 2. then the stove is up to full temperature. and the water isnt moving through the boiler fast enough and so the water starts to boil in the boiler. annoying noise. it doesnt boil too long 30-40 seconds, then its obviously pushed along.
i know the water is moving to slow as.. suppose i hear boiling. i go to the tank and yes the pipe coming from the stove is hot. but the pip out isnt as hot . . unless you had a full tank of water, then yes ill accept boiling. and both in and out is the same temp.

suppose the stove is on for 3 hours.. and 2 people decide to have a shower. . then after words. the pipe out to the stove is stone cold. . as it would be . . but im still boiling water in the boiler in stove. ..

I think if possible. .. a small pump on the line is whats needed!.. you see, to avoid me boiling the water, im having to close off stove vents, but sher thats cooling me stove down!. . .:mad:

any advice welcome.
NBF

muffler

I think this will be more at home in the Plumbing & Heating forum.

Thread moved from C & P.

bbam

Why exactly did he not fit a pump?
I'd be getting a pump installed, the pressure building up will warp your boiler or even rupture it. I presume the pipe size from the boiler is big enough?

Poor Uncle Tom

There should be a pump on the line, imo. As bbam said you run the risk of damage to the boiler if there is not one put on.

No6

You should have a pump with a thermostatic switch on the flow pipe so when the temperature reaches the level you have set it at it turns the pump on!!! We put one in this year and it was banging for the first while, the solution was to turn the temperature down a little so the pump cuts in earlier. It works a treat now!!

DoneDL

NewBeefFarmer, it does sound that either you have air in the system or it`s an issue with poor rise on the pipework not allowing good gravity circulation. I would have thought that a graxity rad should have been installed and why was the gravity linked with the heating system, pics are always good.

NewBeefFarmer

Muffler, cheers for that, didnt know we had a section for plumbing..

bbam:.. yes thats my thinking now, im not a plumper, but looking at it now, its a must. . . i mean the distance alone from the stove to the cylinder is about 3-4 meters. . . cold pipe down under ground, and hot pipe up and over. . but while thers a loop the circulation is not moving quick enough.

Poor uncle tom, . . ya. think ill ring the plumber that fitted and ask why didnt he. .

No6. . . this is the exact thing im thinking of.. and i know it would solve the problem. .. i mean u dont want the pump running when the stove is off, otherwise ull be cooling down the tank with cold water.


DoneDL. .. . . .well. from what the plumber said, we were ok, but just ok with the gravity system . . for me now looking at it. . . ud want the cylinder up higher. .

I dont know the full spec of the gravity system, i know some pipes need to be higher than others. .

thers something up when i hear the boiler boiling water/bubbling and the water cold out pipe from the cylinder is cold after we have a shower. . .it seems to take ages to circulated. .

Thanks all, im ringing me plumber.

gifted

The pipework should be a minimum of 25mm (1")diameter as well for a gravity system

NewBeefFarmer

just to let you know, right now the stove is lit 3 hours. . . its bubbling a bit every 3 mins lately, nothing loud or worrying. but just simering. . . there isnt a huge fire on, just at the moment burning embers at the bottom of the stove . . and guess what. . my pipe in to the cylinder is red red hot, and the pipe out.. . just about. . not even, luke warm (if thats how u spell luke).
ya. . . friggen annoying me.

NewBeefFarmer

gifted wrote: »

The pipework should be a minimum of 25mm (1")diameter as well for a gravity system

yip. . its 1 inch

gifted

sounds like a pump is yer only man so

gifted

if the return back to the stove is risin out of the ground, would there be a possibility of a little air lock in the system?

NewBeefFarmer

gifted wrote: »

sounds like a pump is yer only man so

ya thinkso. ..

I mean hes not the type to take short cuts. . . his work on the house was top class. . . i just think something was miss calculated. . or the stove is faster at heating water than we thought first. ..

ill buzz him in the morning. and ill see what he says. .

thanks again all.

gifted

DoneDL wrote: »

NewBeefFarmer, it does sound that either you have air in the system or it`s an issue with poor rise on the pipework not allowing good gravity circulation. I would have thought that a graxity rad should have been installed and why was the gravity linked with the heating system, pics are always good.

just saw that someone else asked already, apologies

freddyuk

If you have the return pipe going underground (or lower than the return inlet to the boiler ) then you will get little or no gravity flow and airlocks will be a problem. The water will boil in the flow pipe. Much of the heat in the pipe is not the hot water flowing but the heat simply transferring along the pipe from the hot riser. I tried this and it did exactly what yours does.
The flow from the boiler needs to rise directly up and then maybe a short distance horizontal to the inlet of your cylinder. The cool return then needs to flow down back to the boiler without going up hill. Never put anything on the flow pipe that will restrict the flow up to the vent pipe. A pump is used to divert the flow to a radiator, or two, to disperse heat when either the tank is hot enough or the system needs to be cooled down. It is not plumbed onto the flow pipe.

NewBeefFarmer

FreddyUK, i seem to remember all right about this. . .

hold on a second. .

My cold out on cylinder, is lower than my cold in on stove. . . is this correct?. .
from what ur saying. .the system is wrong.

NewBeefFarmer

see pic i made up. .

measurments are as taken . .

pipe run is as what is done . .

stove in one room on plinth. and cylinder in 3 meters away on ground floor level. . plinth is 5 inches high. . .

all measurments are from the ground . . . ie the floor level cylinder is on.


hot pip leaves stove, up and accross ceiling and down, n shaped. and the cold feed is u shaped, down from cylinder accross and up. .

but take a look at the actual measurements.:pac:

aujopimur

A return going under floor and rising to the boiler should not present a problem, I would suggest making sure that there is a rise all the way to the cyl. and that the coil has not become twisted when the fittings were being connected thus restricting the circulation.
Disconnecting the pipework and checking if you can get a marble to roll down thru' the coil will show if it's blocked.

aujopimur

aujopimur wrote: »

A return going under floor and rising to the boiler should not present a problem, I would suggest making sure that there is a rise all the way to the cyl. and that the coil has not become twisted when the fittings were being connected thus restricting the circulation.
Disconnecting the pipework and checking if you can get a marble to roll down thru' the coil will show if it's blocked.

I assumed the cyl was higher than the stove.
It's not going to work until you raise the cylinder.

NewBeefFarmer

Thd cylinder is not higher than the stove, its sitting on same floor same level. . See my picture

freddyuk

I do not think it will work as I tried exactly the same idea and had your symptoms.
I am in a bungalow so put a cylinder right above the stove and it works a treat. The existing cylinder was connected via an indirect circuit to the new cylinder.