New heating zone installed, not getting flow

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New heating zone installed, not getting flow

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andyjennings

Hi, i need some advice on the following: We have a gravity feed central heating system. Today i have run 2 more rads, the only way i could get the rads connected was to T off from the flow and return of another radiator. Water is getting through as i can bleed the rads. The main house rads are all working, but the new two are not. If i undo one of the valves on the new radiators to get a flow, then the heat starts to flow. But as soon as i connect it back onto the rad, they will still not get hot. I am thinking that i may need to fit another pump onto the flow to pull the heat from my main system? am i right? or is there another way? Any help is appriciated. Andy
 
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Turn off all the other rads. If the two new rads now get hot, the system just needs balancing.

How to balance a CH system is the proper way of doing it, but there is a quick way of getting reasonable results.

Remove all TRV heads.
Adjust each lockshield valve (opposite end to TRV) to half a turn open.
Let rads settle down (say 15 mins)
Feel the return (cooler) pipes of each rad
Open the cooler ones by and eighth turn and close hotter ones by the same
Let system settle down again then repeat ad nauseam.
The idea is to get all rad return pipes feeling approximately the same as the boiler return
You can use the boiler return as a guide to how hot the rad returns should be.
 
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I have tried this, but i think that because ive taken the feed for the new rads from the return and flow pipes of another rad, the water is being lazy and just flowing through my loop, and not wanting to divert of towards the new rads. Unfortunatly, i can not get under the floor to divert the flow into the new rads, hence why ive had to take it from the flow and return pipes directly under the rad valves. This is why i think i may need to fit a pump to pull the main flow into the new rads?
 
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Hi, many thanks for the suggestions being made, ive tried turning the rad of where ive taken the feed, doesnt work. I know i havent over loaded the system as in the past ive removed 3 rads from the house, so technically im still one less that i first had.

I shall post a drawing of what ive done
 
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No, call a plumber or heating engineer, it will be quicker & easier !
1. You have not got a gravity heating system if you are going to fit ANOTHER pump, if you have a circulator (pump) it can not be a gravity system but a pumped one.
2. Just because you have removed rads in the past does mean that your newly installed rads will work. The system may not be overloaded but the pipe carrying the heated water to them may well be.
 
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Hopefully this picture may help
 

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That makes sense, didnt think you could overload the rad feed pipe. My system is not sealed, Ie, i have an expansion tank in the loft that fills the rads, with a circulation pump in the airing cupboard. Is there anyway around it, other than calling an engineer
 
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Are you sure the existing pipework is how you have draw it only I thought you could not get under the flooring to make a connection ????
The reason I ask is what you have drawn is a one pipe system & you have taken a flow & return off it (in a two pipe arraignment) it will never work like that?
 
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Hi chris, ive taken the new feed from the pipes that feed the existing rad, just below the valves. Im assuming that its not drawing enough flow, hence the water is being lazy and sticking to the existing loop. My thoughts was to fit a thermostat and circulation pump into the new zone (New zone is in a garage room to keep it warm) to pull the flow though into the new rads.
 
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Andy, with all due respect you are out of your depth, get somebody in to have a look. If the pipework is installed as you drawn it sticking another pump on it will not work. Trust me.
 
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doitmyself said:
Turn off all the other rads. If the two new rads now get hot, the system just needs balancing.

How to balance a CH system is the proper way of doing it, but there is a quick way of getting reasonable results.

Remove all TRV heads.
Adjust each lockshield valve (opposite end to TRV) to half a turn open.
Let rads settle down (say 15 mins)
Feel the return (cooler) pipes of each rad
Open the cooler ones by and eighth turn and close hotter ones by the same
Let system settle down again then repeat ad nauseam.
The idea is to get all rad return pipes feeling approximately the same as the boiler return
You can use the boiler return as a guide to how hot the rad returns should be.
Click to expand...

After all that, please go back to 2nd post & follow instructions given by doitmyself.
 
Last edited:
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it all comes down to pipe sizing, length of pipe ( resistance to flow ) and balancing
a 15mm pipe will carry about 6kw, 10mm only 2.5kw, 22mm 13kw etc
the longer the pipe the more resistance to flow, possibly the need for the pump to be turned up to an appropriate speed.
but also the need to balance the whole system so that all radiators heat up to the same degree at the same time.
you don't need a new pump, you just need to do the job correctly.
 
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Thanks guys, except for the comment by dannyparty that doesnt help at all, and just screems a bad tradesman. Ive balenced the system, used 15 mm pipe and tried every thing suggested before asking for assistance. I shall go back to my original post. I am not getting flow into the new zone due to the flow being lazy. If i draw the flow out of the new zone, heat flows nicely. As its in a completly diff part of the house, im not concerned if its on all the time, hence why i have asked if my thoughts on fitting a pump with a thermostat and fused spur, so that when that room drops below temp, i can either choose to turn it on, or leave it off. If turned on it will pull the water from the flow, very much like a wet underfloor system.
 
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you should be getting some heat with that setup even if it takes a while to get through if your getting no heat something isnt as youve drawn it have you checked there is flow of water from both sides of the rad ?
 
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Explain how you mean draw the flow out? Water takes the easiest route as you said (lazy) there could possibly be a blockage restricting circulation in the new pipe work to your new rads not likely but possible. Turn all rads off in the house apart from the two offending radiators. And I apologise for my previous post.
 
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I agree with above ^^ but the flow will not be "lazy" if it is a pumped circuit & there are no blockages & everything is balanced right.
If it is a gravity rad system, any rads piped to it will have to be piped very carefully or won't work.
 
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