Back boiler

[donnysparks]

Hi all,

I've been asked to install a thermostat to a back boiler to control the Central Heating and Hot Water. All there is just now is a coal fire a HWC & a Pump under the floor next to the coal fire where there is also a fused spur controlling the pump.
The problem they have is when they switch the spur which operates the pump which circulates the water round the rads the cylinder isn't getting hot. Also when they go to work they cant leave the spur on because they won't have any HW meaning that if they leave it off to heat the cylinder they won't have any heating for when they get home.
Am I right in saying a cylinder stat wired back to the pump using the stat as a switch to bring on the pump for the heating when the cylinder reaches temp would be satisfactory? Never done this before so any help would be great.

Cheers

Donny

 

[monkster]

I thought hot water would have been gravity fed and the pump's job is to ciculate hot water round the radiators,are you sure it's piped right ?

 

[donnysparks]

No idea mate this is how there telling me it works, the pump just does the heating!!

 

[jaydee81]

system is gravity hot water but when pump is on it draws the heat away from the cylinder and around the rads control the pump using a pipe stat on return pipe to boiler

 

[donnysparks]

Thanks jaydee81 that makes sense although how do I know what ones the return, not sure in the plumbing side?

 

[jaydee81]

when boiler is lit should be able to tell by touch return will by colder

 

[donnysparks]

when boiler is lit should be able to tell by touch return will by colder

Magic mate thanks!

 

[FrankUK]

Have you checked next to the hot water cylinder to see if there is a 2 or 3 port valve installed?

 

[donnysparks]

Have you checked next to the hot water cylinder to see if there is a 2 or 3 port valve installed?

No valves installed frank

 

[keniff]

I'm sure you have to have hot water and heating on at the same time if you want heating, and just use stat to control pump. Stat on the tank controlling boiler itself. Been ages since I saw one though

 

[ruston]

Is this fire on tick over all day, or is it just allowed to burn down? If the latter they will have a problem maintaining hot water and heating unless it is a super dooper boiler.
Heating will take priority if the pump is called for heating all day and the temperature is not met (roomstat) . As has been said the hot water will just be gravity and get no flow.hence will not heat the water, whilst the heating will just be pumping round ever cooling water.

 

[donnysparks]

Yeah the fire just gets lit then left to burn out and they turn the pump off when they go to bed so the cylinder gets hot! Seems a really rubbish system!

 

[Geordie Spark]

when boiler is lit should be able to tell by touch return will by colder

and when you fire the boiler up, the flow pipe will get hot first (i.e. before the return)

 

[ruston]

Yeah the fire just gets lit then left to burn out and they turn the pump off when they go to bed so the cylinder gets hot! Seems a really rubbish system!

It is , you are on a hiding to nowt , if they crack that they will make a fortune.

 

[oldtimer]

Looks like you have a gravity hot water system and a pumped heating system so ho do you know well there should be 2 28mm copper pipes running the the immersion. You say there is no 3 way control valve so lets go back to basic. When the system was put in all the radiators just had isolation valves and you had a timeclock with 2 settings 1 hot water 2 hot water and central heating. The thermostat on the boiler was set to 60-65oC and that would have been that. plus if there was a room stat that would have been wired in series from the timeclock to the pump.

So the old way would have been the timeclock hot water putting a switched feed to the boiler so the immersion would heat up to the boiler temperature then if you wanted the central heating on the timeclock 2nd channel would switch on the pump . As for the room stat well that just means to take the timecloclock 2nd channel supply to the pump and reroute it to the room stat then get the room stat to switch the pump on.

Remember the room stat should be fitted in a room ie hall or lounge and the radiator should not have a TRV fitted plus always run a 3 core and earth to the room stat 1. Feed from timeclock 2.switch feed to pump. 3. neutral connection for anticipator resistor on room stat 4. Earth cable