pumped system pumping over

[eddiebrown424]

Hi all,

I went to look at a job today in which the header tank is full of hot water and overflowing.

There is back boiler and the pipework runs upstairs to the cylinder but i can see no valves. I did not want to take out the fire and told the customer that I would prefer to do some research away from the job. Is there such a system (excuse my naivity) where there are four ports comming off the boiler for primary and secondary circuits. The system is around 30 years old and at this point i did reccommend an upgrade as in my thinking there could be several issues and it may be more financially viable/ sensible to put in a combi although i would like to resolve the problem if possible

I thought that the issue could be,

A blockage---- solution powerflush or cut out the affected pipework
overheat stat on the boiler failing although this did switch on and off when tested.
pump in the wrong position the pipe layout is not something I have encountered before i.e the primary 28mm going straight to the cylinder and returning to the boiler. with the 22 mm secondary pipework not visibly connected i.e. through a motorised valve.
A really long shot.... a split coil although i am sure Central heating water would enter the hot water and not the other way round.

I cannot see a by-pass on the system lthough i assume that if all circuits are connected at the boiler it may not need one. Also I could not see any motorised valves although i only called in as it was a friend and i stupidly thought the problem was going to be the ball valve in the cwst and a quick fix.

any advice really appreciated.

I do have some pictures but most pipework is hidden as is the boiler. I found this and not sure if it helps

https://www.google.co.uk/search?q=p...2eV1xCIbM:&usg=__dUBpzTOWixg8_GNCDJmeNln53-0=

 

[stevetheplumber]

you have gravity hot water and pumped heating probably the boiler stat is to high did it switch of when lowered is the immersion heater switched on as well as the boiler very simple system

 

[eddiebrown424]

Hi Thanks stevetheplumber. In all honesty I didnt see an immersion heater but I could only get to half the cupboard. I only just found the schematics for it and it does look simple. I will check for an immersion and try to turn down the stat on the back boiler. I have turned down the pump to mid setting do I need to turn this back up. Also as usual I got my terminology wrong and the feed pipe is red hot I think this is different than pumping over. Just as a learning curve are there diverter valves in the boiler or does the pump which appears to be on the return just pump through the burner. Does the fact that the cold feed is red hot lead to another diagnoses? Thanks for the help

Eddie

 

[jtsplumbing]

Is small expansion tank lower than water level in big tank if so could be faulty coil in cylinder, if you don't understand these old systems, still plenty of them around and still work, do you know any older plumbers in your area who can help with some advise,
you need to get an understanding of these basic systems, Please don't go down the route that a combi is the be all & end all of systems, older people love the simple systems, It would be of benefit to you to do some reading on how gravity heating & hot water systems work, and would help with your choice of upgrading old systems other the just fitting combi's, Must be someone on here who you could go with now and then to get to grips with these systems, what area are you in ?

 

[jtsplumbing]

For your information pump only runs heating system, is it pumping over ? or getting hot when just on for hot water , graviting around expansion tank ? this could indicate a split coil in cylinder as B4 where is expansion tank positioned

 

[eddiebrown424]

Hi jts plumbing Im in middlesex and i would take anyone up on that offer i'm the first to admit I have learning to do. I understand the concept of both y plan nd s plan even if the wiring may take a while but I couldnt understand that with no diverter valve you could have a choice of heating only but there is a two way programmer so i thought there must be one somewhere. I worked on one job and the plumber had put it under the floorboards in the middle of nowhere... lol. I love the old s plan system and also unvented but a combi seems a much more efficient way of going as they only have two beds and a bathroom and seeing a tank full of red hot water above the ceiling scared the cr.p out of me if im honest hense trying to resolve the issue asap. Thanks for the help guys.

Eddie

 

[eddiebrown424]

Hi again jts sorry cant type that fast lol. The header tank is below the cwst. The system had finished overflowing when i got there i put it on after turning the pump down and it fired ok with no overflowing. Much as I thought it could be a split coil I was unsure how to test for it but thnks to guys on here getting a bit of a grip on it. Would still love to learn from anyone on site though. Thanks again Eddie

 

[stevetheplumber]

pump is usually either in the casing on one side of the chimney breast or under the floor in roughly that area ,gravity f and e tanks do tend to get warm i read a lot about split coils on cylinders on here but have only ever seen one and that was faulty from new turn of the cold feed to the cylinder and if it stops the back filling then it is
you always run the pumps as low as you can and still get hot rads

 

[eddiebrown424]

thanks stevetheplumber. The water is red hot i nearly made a cup of tea whilst I was up there lol.
I will do the tests for a split coil and also check the vent is high enough. Last silly question there has to be a diverter valve doesnt there? I couldnt see one but how else do you only have hot water?.,.,.,., Thanks again Eddie

Eddie

 

[jtsplumbing]

What programmer does on these systems Hot water just powers up boiler, temperature is then controlled just with boiler stat, for heating same as hot water but switches on pump, if your lucky it may be wired to a room stat, but you cant have heating only, just hot water or both, over the years different ways of controlling hot water have been used until it got to using motorised valves, keep an eye out for the old twin pump method (SMC) control pack

 

[jtsplumbing]

Raze up expansion tank above cwst

 

[eddiebrown424]

Thanks JTS also looking into it there are no vlves tara.... only pump comming on that works rads seems a really simple but wasteful system... Thnks all Eddie

 

[jtsplumbing]

Believe me back in the early 70s that was the bees knees, most people didn't have heating, thought to be posh if you had a multi point water heater

 

[eddiebrown424]

seems so antiquated now... youd think the problem would be easy to dignose with such a simple system....lol.. Unsure of the programmer mke and model but they must be really posh because thay have a room stat.....

Thanks again all ;-)

Eddie

 

[eddiebrown424]

sorry guys on an s plan for example the pump is on the flow with the flow going towards the cylinder (hope im right its been a while) on the above diagram should the arrow be facing the rads as if on the return and pumping the other way would it not push wter through the burners and increase the chance of pumping over as it is pumping towards the vent pipe.

Thanks again

Eddie