Central Heating Comes on with Hot Water, Help

[MichaelwGroves]

I have got a 'Y' plan system that has been added to over the years. Unfortunatly by me, so I am to blame for this mess. Started off with old boiler, then big extension required more radiators, bigger boiler and bigger pump.
I'm not sure when it started to go wrong, it was subtle but is getting worse.
At first just the bathroom tail rail would get hot when hot water on. I initially thougt I had connected up wrong as I could not get to pipe work to be 100% sure where to connect upto, but it was not a big problem. Then during the extension I was able to remove part of the ceiling to expose my error, plumbed into correct place as I thought but still got problem. I thought it must still be connected wronmg, but still could not get to all pipework so left it until later in the build. Added some more radiators which got very slightly warm when hot water on. Anyway, I was sure they were plumbed in okay so thought it was 3 way vale was faulty, eplaced this, but still got problem.
Then bolier started getting over heat errors, engineer replaced sensors but I still got errors. He advised pump was not powerful enough, so I spent £600 on big Grunfos pump. This made it worse, so had to turn down to setting 2 to get it to not trip boiler. Engineer then advised mast be short in plumbing, but could not see where without lifting floors etc.
Okay, so now I'm at the stage where I can expose nearly all pipes and I can see how water is flowing along the return, through the bathroom towel rail, out of the flow, through next radiator, then returns to the boiler.
So I turn off towel rail to prove my theory but other radiators still get warm.

So I'm throwing the towel in to the experts, I just can't see the wood for the tree's. I've attached a diagram with a few lables to aid conversation. Anything to the right of the wall is difficult to connect upto today, anthing to the left is very easy to change. I would really appreciate any comments.



Thanks
Michael

 

[erpkid]

It is your return from the cylinder 5 should be before 1 as this is causing secondary circulation. Re-routing will solve this.

 

[jase158]

which ones are getting hot when hot water on?

 

[MichaelwGroves]

All get warm, Towel Rail gets hot.

 

[RGII79]

you must have two returns pipes on towel rail make sure the feeds to towel rail are from a flow and a return

 

[jase158]

It is your return from the cylinder 5 should be before 1 as this is causing secondary circulation. Re-routing will solve this.

I cant see this as there is no circuit still?

 

[RGII79]

pipe connection 5 to return pipe below connection 4 shud solve

 

[erpkid]

pipe connection 5 to return pipe below connection 4 shud solve

Yes anywhere on the return as long as it is before 1. Just depends on the access as it is strange that this was not done initially. Hopefully the op has good access.

 

[Billy Bob Bob]

why does the return go into the top of the coil?

 

[MichaelwGroves]

Thanks for your thoughts guys,

why does the return go into the top of the coil?

Surly it's coming "from" the top of the coil as the start of the return?


Just to confirm the draweing is accurate, the towel rail is connected to both flow and return.


Moving '5' before '1' will be a problem, but if this is the soloution it can be done, but I can't see how this will fix it, please explain.

Thanks
Michael

 

[MichaelwGroves]

Just to confirm, any plumbing to the left of the wall is easy, anything to the right is difficult.

 

[jam1979]

is your 3 port valve not nackered i e staying in midposition

 

[MichaelwGroves]

I don't think so, I previously had this problem so replaced the valve but nothing changed.

 

[joe brown]

it sounds like ur valve is knackered to me allowing the hot water to flow through both CH and HW...that would be my first point of investigation rergardless of how new it is

 

[MichaelwGroves]

I'll be annoyed if it is, because that's what is was supposed to fix. I'll do a touch test this weekend and see for sure, but I am doubtful. I think I have just plumbed wrong.

Moving point 5 has been mentioned twice, the more I look of it I think this is the problem, but I think the fix is to move to point 2?

 

[erpkid]

When you select hot water the flow goes through the coil then back to the boiler. Because you have a tapping after this there will be secondary circulation - the secondary circulation will make flow and returns reverse. To test this you could fit a valve on 5 before it gets to the return on the boiler ( your new rads will not work at all then but the solution will be clearer ) . By re-routing 5 anywhere on the return side before 1 the return from the boiler will have a direct route when hot water is selected and secondary circulation will go. The in cylinder coil flow is wrong , this may be just the drawing , but that will not affect the solution just the efficiency.

 

[erpkid]

I'll be annoyed if it is, because that's what is was supposed to fix. I'll do a touch test this weekend and see for sure, but I am doubtful. I think I have just plumbed wrong.

Moving point 5 has been mentioned twice, the more I look of it I think this is the problem, but I think the fix is to move to point 2?

2 would work as would any point before this. It depends how easy it is to access.

 

[erpkid]

I'll be annoyed if it is, because that's what is was supposed to fix. I'll do a touch test this weekend and see for sure, but I am doubtful. I think I have just plumbed wrong.

Moving point 5 has been mentioned twice, the more I look of it I think this is the problem, but I think the fix is to move to point 2?

Even if you fitted a brand new valve you would still have the problem.

 

[buckley plumb]

dont they taech the 3 tee rule at college now or is it just combis :8:

 

[MichaelwGroves]

dont they taech the 3 tee rule at college now or is it just combis :8:

Enlighten me?

 

[erpkid]

Enlighten me?

Google it. You will see how it relates to your current layout and what you need to do. Forget the bypass bit as you are Y plan though.

 

[MichaelwGroves]

Brilliant, that makes perfect sense now. '5' is definantly in the wrong place. I'll move somewhere around point 2 this weekend and let you know how it goes.

I'll also confirm cylinder flow when I get home, so flow should go in the top and out bottom, is that what you are saying?

Co's I would have thought the other way around, my thought is hottess water should enter bottom first?

 

[erpkid]

Brilliant, that makes perfect sense now. '5' is definantly in the wrong place. I'll move somewhere around point 2 this weekend and let you know how it goes.

I'll also confirm cylinder flow when I get home, so flow should go in the top and out bottom, is that what you are saying?

Co's I would have thought the other way around, my thought is hottess water should enter bottom first?

Top entry is usual and most efficient.

 

[MichaelwGroves]

Just done a quick google, this was the first post I found, so not conclusive, but they say;

"On fully pumped systems it doesn't matter"

Would you agree?

 

[MichaelwGroves]

Just checked, cylinder is bottom fed.