Central Heating Issue- Downstairs Rads

rustbucket

Hi. I have an issue with my heating system and looking to see if anyone can shed some light or thoughts? I have a plumber investigating at the moment but he is stumped.

Bought house a couple of years ago with old oil boiler in an outside boiler house.
All rads worked fine.

As part of refurbishments we converted to gas and because all the floors downstairs were concrete (plus the missus didnt want the boiler in the kitchen) we installed a new gas boiler in the side attic (seems odd I know but after discussing it with the RGI we hired at the time he assured us there wouldnt be any major issues)

He disconnected old boiler and capped pipes in old boiler house and must have made new connections (flow, return and water cyclinder) in the attic

As a result the rads heated in reverse. Upstairs got hot first then downstairs slowly.

The original RGI never balanced the rads and never came back to do it after a year of chasing. I eventually gave up and made a job of it myself.

Anyway to cut to the chase we recently demolished the old boiler house and realised that he didnt actually disconnect the old boiler pipes from the system her just capped them off.

New plumber came in to have a look, as we wanted to balance system, instal thermostatic valves and demolish old boiler house.

At present all the rads now have thermostatic valves installed.

All the rads upstairs get hot. only 3 downstairs get mildly warm. We cannot get a flow of hot water to the rest downstairs

The system has been drained
He has changed the water to mains fed rather than tank fed to boost pressure
A Magnaflow system has been added
All rads upstairs turned off to push flow downstairs
System topped up and all rads have been bled. No airlock or air in system.

Rads downstairs still not getting hot other than the three ones that only get luke warm.

Has anyone got any ideas?

Im wondering would it have anything to do with the old flow and return from the old boiler as these are obviously still linked to the system

Heat must be going from boiler down to outside boiler house, loop back in upstairs then back downstairs??

I know this is a long post so apologies for that. Does anyone have any ideas?

John.G

rustbucket wrote: »

Hi. I have an issue with my heating system and looking to see if anyone can shed some light or thoughts? I have a plumber investigating at the moment but he is stumped.

Bought house a couple of years ago with old oil boiler in an outside boiler house.
All rads worked fine.

As part of refurbishments we converted to gas and because all the floors downstairs were concrete (plus the missus didnt want the boiler in the kitchen) we installed a new gas boiler in the side attic (seems odd I know but after discussing it with the RGI we hired at the time he assured us there wouldnt be any major issues)

He disconnected old boiler and capped pipes in old boiler house and must have made new connections (flow, return and water cyclinder) in the attic

As a result the rads heated in reverse. Upstairs got hot first then downstairs slowly.

The original RGI never balanced the rads and never came back to do it after a year of chasing. I eventually gave up and made a job of it myself.

Anyway to cut to the chase we recently demolished the old boiler house and realised that he didnt actually disconnect the old boiler pipes from the system her just capped them off.

New plumber came in to have a look, as we wanted to balance system, instal thermostatic valves and demolish old boiler house.

At present all the rads now have thermostatic valves installed.

All the rads upstairs get hot. only 3 downstairs get mildly warm. We cannot get a flow of hot water to the rest downstairs

The system has been drained
He has changed the water to mains fed rather than tank fed to boost pressure
A Magnaflow system has been added
All rads upstairs turned off to push flow downstairs
System topped up and all rads have been bled. No airlock or air in system.

Rads downstairs still not getting hot other than the three ones that only get luke warm.

Has anyone got any ideas?

Im wondering would it have anything to do with the old flow and return from the old boiler as these are obviously still linked to the system

Heat must be going from boiler down to outside boiler house, loop back in upstairs then back downstairs??

I know this is a long post so apologies for that. Does anyone have any ideas?

If the flow and return to old boiler house are capped off how are they still linked I wonder?. If they are and the water is short circuiting then there should be little difference between boiler flow and return temperatures, can you feel them with the downstairs rads only on and the cylinder coil balancing valve shut.
Is the boiler only running for a few minutes and then cutting out (cycling) in this mode?

You say you have thermostatic valves fitted, are there any motorized valves fitted, ie any form of zoning?

"Water was changed to mains fed to boost pressure", you should have a pressure gauge somewhere (sometimes in the boiler display panel) and it should be reading > 1.0 bar.

Is the circulating pump external to the gas boiler or is it internal, if its internal, then a RGI I think is the only one who can look at its settings as the boiler panel has to be removed.

I think most gas boilers have internal automatic bypass vales fitted to allow a flow through the heat exchanger on each boiler shutdown but its possible that you have a external one that needs adjusting.

You say you are happy that there is no air in the system.

Can't think of anything else just now and your plumber may have checked these out all ready anyhow.

Edit: Ensure as well that the downstairs rads/pipework are free of sludge etc, was the system flushed/cleaned out on boiler changeover.

rustbucket

Thanks for the reply. Im sorry I dont know how to quote and respond to your questions but Il try to answer below

Originally when the old boiler was disconnected the RGI left the pipework in the boiler house. 3 pipes were coming out of the ground, 2 of them looped. They were capped at the point where they connected to the old boiler and left in place. This allowed for the old boiler to be removed. The new boiler was installed in the attic and assume it was connected at new points into the system. I suppose what he should have done was find the point inside the house where these connections then ran outside and sealed it off at that point.

My new plumber asked if those pipes ever got hot in the old boiler house to which I couldnt remember. I assumed no as I thought they were properly disconnected.

These pipes were subsequently cut and all capped. It was only after that that the plumber realised they were probably still part of the loop and he re connected two of the pipes together as they were originally looped. I hope that makes sense?

There is almost no difference in the new connection between boiler flow and return. We though that possibly the motorised valves (2 of them- new installs with new system) were gone but these are working fine. The boiler does switch off but thats because I think its linked to thermostat? If we turn it right up it stays on for a bit longer but assume thats because thermostat reaches temp upstairs.

The system is zoned for heating and water. No zones for upstairs/downstairs

Pressure was 1 bar and is still 1 bar even though it has now changed to mains supply so no problem there

Im not sure about circulating pump but assume its internal. Would this be an issue? It would seem odd as if I thought there was a problem with that we would have an issue with heat in all rads. All the rads upstairs (when on) get piping hot and the water cylinder has no issues with hot water.

I assume the system was cleaned and flushed with the new boiler install. I would be disappointed if not.

Its going to be done again anyway but plumber wanted to check it wasnt an airlock or leak before doing that as it would involved draining the system and he didnt want to waste in unessecarily.

Would it matter which pipes were looped originally at old boiler? There were three. I know it would matter but thought if wrong ones looped we would get no heat to rads at all. At present all rads heat upstairs but only 3 get mildly warm downstairs

Thanks for taking the time to read

John.G

rustbucket wrote: »

Thanks for the reply. Im sorry I dont know how to quote and respond to your questions but Il try to answer below

Originally when the old boiler was disconnected the RGI left the pipework in the boiler house. 3 pipes were coming out of the ground, 2 of them looped. They were capped at the point where they connected to the old boiler and left in place. This allowed for the old boiler to be removed. The new boiler was installed in the attic and assume it was connected at new points into the system. I suppose what he should have done was find the point inside the house where these connections then ran outside and sealed it off at that point.

My new plumber asked if those pipes ever got hot in the old boiler house to which I couldnt remember. I assumed no as I thought they were properly disconnected.

These pipes were subsequently cut and all capped. It was only after that that the plumber realised they were probably still part of the loop and he re connected two of the pipes together as they were originally looped. I hope that makes sense?

There is almost no difference in the new connection between boiler flow and return. We though that possibly the motorised valves (2 of them- new installs with new system) were gone but these are working fine. The boiler does switch off but thats because I think its linked to thermostat? If we turn it right up it stays on for a bit longer but assume thats because thermostat reaches temp upstairs.

The system is zoned for heating and water. No zones for upstairs/downstairs

Pressure was 1 bar and is still 1 bar even though it has now changed to mains supply so no problem there

Im not sure about circulating pump but assume its internal. Would this be an issue? It would seem odd as if I thought there was a problem with that we would have an issue with heat in all rads. All the rads upstairs (when on) get piping hot and the water cylinder has no issues with hot water.

I assume the system was cleaned and flushed with the new boiler install. I would be disappointed if not.

Its going to be done again anyway but plumber wanted to check it wasnt an airlock or leak before doing that as it would involved draining the system and he didnt want to waste in unessecarily.

Would it matter which pipes were looped originally at old boiler? There were three. I know it would matter but thought if wrong ones looped we would get no heat to rads at all. At present all rads heat upstairs but only 3 get mildly warm downstairs

Thanks for taking the time to read

I still don,t understand how the pipes are both looped and capped. As I said above, if they are looped then the water will just take the easiest path and by pass the rads but as you say the upstairs are fine so a bit of a mystery there. Originally, with the oil boiler installed, one of these pipes should be the Flow (out) from the boiler, the other should be the Return back to the boiler, they should be either 1 inch or 3/4 inch pipes, I don,t know what the third pipe is/was except just maybe the system make up water or the oil supply pipe, either of these would only be ~ 1/2 ins.
I know that your plumber asked you if these pipes ever got hot, can't you just start up the system (now) and just feel them, if they are short circuiting then they will heat up very rapidly.

I would be surprised if the thermostat, if turned to maximum (30C?) would reach its set point and cut out the boiler, the boiler is more than likely cutting out on its own boiler stat but you can turn off all the upstairs rads and then it wont have much effect.
Can you shut off the upstairs rads, switch off the hot water zone and switch on the heating zone and see if there is much difference in the flow & return at the gas boiler, if both get very hot within a few minutes of boiler start up then
obviously there is no circulation through the downstairs rads and the boiler will cut out on its own stat in a very short time.

Re the circ pump, its probably OK but some of these can be switched to Auto (maybe not on gas boilers) and can modulate down to give a very low pumping head which may affect the circulation but again its OK on the upstairs rads.

Edit: I understand now what you are saying now re pipework capping and linking, well if those two pipes are the Flow & Return then they should certainly should not be joined/linked now IMO.

rustbucket

Sorry I am not being very clear

The old boiler system did indeed have a flow and return. Both of these were 1 inch pipes. When the boiler was removed we were left with network of pipes.

3 pipes came up from the ground (all under the patio and led into the house)- all 1 inch. 2 of these joined together and were capped. One on its own and this was capped. This is how it was left in the old boiler house until we decided to knock it down.

Up until April the new heating system worked fine although not balanced right. We have not had the heating system on since then.

When we decided to knock the boiler shed we needed to re cut the old boiler pipes and bury them under the ground. The pipes were re cut and 3 separate caps were put on. When we realised our mistake we couldnt remember which of the two were joined together so the plumber made an educated guess and reconnected the two he thought were oringally connect. Thats what I meant by looped

Since then the heating was turned on , upstairs working but dowstairs as described.

We are now thinking that perhaps the two 1 inch pipes he joined may have been the wrong ones but that would mean that no rads downstairs should get any heat rather than 3 getting slightly warm

He is now going to drop a couple of rads to see for sure that there is no air or sludge. He thinks maybe a couple of the returns might be slightly higher than they should be. If that doesnt work Im not sure where to go an how to go about fixing the rads downstairs

John.G

rustbucket wrote: »

Sorry I am not being very clear

The old boiler system did indeed have a flow and return. Both of these were 1 inch pipes. When the boiler was removed we were left with network of pipes.

3 pipes came up from the ground (all under the patio and led into the house)- all 1 inch. 2 of these joined together and were capped. One on its own and this was capped. This is how it was left in the old boiler house until we decided to knock it down.

Up until April the new heating system worked fine although not balanced right. We have not had the heating system on since then.

When we decided to knock the boiler shed we needed to re cut the old boiler pipes and bury them under the ground. The pipes were re cut and 3 separate caps were put on. When we realised our mistake we couldnt remember which of the two were joined together so the plumber made an educated guess and reconnected the two he thought were oringally connect. Thats what I meant by looped

Since then the heating was turned on , upstairs working but dowstairs as described.

We are now thinking that perhaps the two 1 inch pipes he joined may have been the wrong ones but that would mean that no rads downstairs should get any heat rather than 3 getting slightly warm



He is now going to drop a couple of rads to see for sure that there is no air or sludge. He thinks maybe a couple of the returns might be slightly higher than they should be. If that doesnt work Im not sure where to go an how to go about fixing the rads downstairs

Its a conundrum all right.

With three 1" pipes then it looks like the flow or return from the downstairs rads might have been extended out to the old boiler house and then teed in to the Boiler flow or the Boiler return as appropriate. The only other reason that I can think of for the "third" pipe is that it was a vent pipe carried all the way up to the header tank, what did your plumber think of the three pipe arrangement?.
Your system worked after initially removing the oil boiler so the link was obviously required. With any two pipes linked & capped and the remaining one capped then there is only three possible combinations..pipe1&2 linked&capped and pipe3 capped. Pipe1&3 linked&capped and pipe2 capped. Pipe2&3 linked&capped and pipe1 capped. One of these combinations did work so if all else fails (or even try it first) then by numbering the pipes, each combination can be tried out, I know its time consuming with drain down and refilling etc but it will tell you something?. Of course I suppose its possible that the heating zone valve is only supplying the upstairs rads but one would then expect the downstairs rads to work if the hot water zone valve was opened but every option will have to be looked at.

In your Post No3 you said that with the downstairs rads only on (upstairs rads shut off & hot water zone off?) that "There is almost no difference in the new connection between boiler flow and return", I take it that you are saying that both flow&return pipes are very hot?

rustbucket

Sorry

Ignore that bit from post no 3. With the downstairs rads on and the upstairs (and water off) there was no difference in the heat of the downstairs rads at all (they were the same as when the upstairs rads were on). We turned the upstairs rads and water off to force the heat downstairs but it made no difference. (in both instances only 4 of 10 rads downstairs warmed up- albeit only a tiny bit)

When I mentioned the boiler flow and return I was referring to the in and out of the motorised valve for the rads as we initially thought the valve was bust. My error

I think you may be right that 2 of the 1 inch pipes are the flow from the old boiler (possibly branched off 1 for upstairs and 1 for downstairs) and 1 is the return.

What I dont understand is though if the wrong pipes are looped (as in one flow to a return) wouldnt that affect the whole system? as in all the rads and water wouldnt work? Unless the new boiler is piped in where by there is an new flow and return into the upstairs rads and that the pipework outside now only affects the rads downstairs. As in flow from boiler goes upstairs, then out to old boiler house then in to downstairs rads?

My plumber was supposed to be back on Thursday to investigate further but didnt make it

John.G

rustbucket wrote: »

Sorry

Ignore that bit from post no 3. With the downstairs rads on and the upstairs (and water off) there was no difference in the heat of the downstairs rads at all (they were the same as when the upstairs rads were on). We turned the upstairs rads and water off to force the heat downstairs but it made no difference. (in both instances only 4 of 10 rads downstairs warmed up- albeit only a tiny bit)

When I mentioned the boiler flow and return I was referring to the in and out of the motorised valve for the rads as we initially thought the valve was bust. My error

I think you may be right that 2 of the 1 inch pipes are the flow from the old boiler (possibly branched off 1 for upstairs and 1 for downstairs) and 1 is the return.

What I dont understand is though if the wrong pipes are looped (as in one flow to a return) wouldnt that affect the whole system? as in all the rads and water wouldnt work? Unless the new boiler is piped in where by there is an new flow and return into the upstairs rads and that the pipework outside now only affects the rads downstairs. As in flow from boiler goes upstairs, then out to old boiler house then in to downstairs rads?

My plumber was supposed to be back on Thursday to investigate further but didnt make it

You said in post no1 that the new gas boiler is installed in a side attic, I assume that it is installed upstairs? and if so then the upstairs rads may be OK but downstairs if pipes are looped incorrectly ie flow to flow or return to return then the rads downstairs would act like a one pipe system and might just get lukewarm.
One other thing comes to mind, you might just remove the thermostatic control valve sensors and push the operating pin in and out a few times to ensure that they are free, its highly unlikely that they are sticking shut but worth checking, when finished leave all the settings at 5 (fully anticlockwise)

rustbucket

John.G wrote: »

You said in post no1 that the new gas boiler is installed in a side attic, I assume that it is installed upstairs? and if so then the upstairs rads may be OK but downstairs if pipes are looped incorrectly ie flow to flow or return to return then the rads downstairs would act like a one pipe system and might just get lukewarm.
One other thing comes to mind, you might just remove the thermostatic control valve sensors and push the operating pin in and out a few times to ensure that they are free, its highly unlikely that they are sticking shut but worth checking, when finished leave all the settings at 5 (fully anticlockwise)

Thanks for all the help. It turns out the system needed to be cleared of sludge as well as the correct pipes looped from the old boiler. All sorted now so m