Is my water tank plumbed in upside down?

[judderi]

First i will explain the problem. I have a standard gas boiler that runs the radiators and hot water. The radiators have always ran fine. However the indirect water system has issues. When heating the water the system will heat and heat until the water boils and has no other option to rise up the overflow and empty into the header tank. The boiler will then cut out cool down and repeat the process. At first i blamed the hot water cylinder as it was severly limed up. However this has now been replaced for a brand new cylinder and the problem remains. My theory is this, as the water system is a gravity setup i suspect that the pipes to the tank are the wrong way round. I would suspect that the top pipe coming from the boiler was the hot and should feed into the lower intake on the water cylinder. The hot water would then rise up the coil heating the water, cooling as it goes and be forced out the top pipe back down to the lower pipe on the boiler. Am i right here? The reason i ask is becuase my system is the other way round i.e the hot from the boiler enters the top of the cylinder. So i suspect that the hot water is simply staying at the highest point and eventually going all the way up the overflow back into the header tank.

If my theory is correct it will be a simple matter of swiching the pipes over at the boiler.

Whats your opinion guys and gals?

 

[ChrisR]

You appear not to understand how it works, assuming it's a normal indirect system.
The hot water from the boiler only goes into a COIL OF PIPE in the cylinder, to heat the water indirectly, then back to the boiler. We can argue about it, but it doesn't make much difference which way the boiler water goes through the coil.

The boiler can't (~) get hot enough to get water coming out of the HW cylinder vent.
- are you sure it isn't also being heated by an electric immersion heater?

Does your cylinder say "Primatic" on the side?

How many tanks do you have in the loft, if big and small which one is hot water circulating into?

Edit - most of this doesn't apply - his pump is US - see other post.

 

[judderi]

Hi thanks for the reply. 1st i think we may have crossed wires. Yes my pump is also shagged but this only powers the radiators and i had the hot water problem long before the pump gave up. The Hot water system is gravity fed.

Yes my water cylinder has a coil. No i dont have an imersion. I have 2 tanks. 1 large to fill the cylinder and 1 small to fill the central heating system. My tanks are not in the loft, they sit in the same cubbord as the cylinder. The large tank is the 1st with the smaller above.

Its not the water in the cylinder that is boiling up but the water in the coil or the feed to the coil. My feed has a T piece. The large pipe goes to the cylinder coil and the small pipe is the overflow that goes up to my small header tank. The water boils and raises up this overflow into my small header tank.

I hope this cleares a few misunderstandings. Any more ideas?

 

[weareleeds]

Are you not aware that it is against part l to leave a gravity cylinder in without any kind of control. I would go for a fully pumped upgrade depending on age & condition of system & boiler or consider a combi

 

[kevindgas]

how many pipes go to header tank ?
where do they join the heating system/boiler?

firstly the F+E tank does it have a 22mm vent and a 15mm feed pipe if it does and these are incorrectly joined into the system, then you will get pumping over, this in turn leads to air in system which in turn leads to corrosion

the easy fix for this is to get rid of the 15mm feed and combine the open vent and feed into the 22mm pipe

secondly try cleaning out the system as i expect it is black drain down and refill, then put in a cleanser leave in system for a day and the drain again, refill with water and add an inhibitor

 

[judderi]

Thanks.

1. wareleads - sorry but i don't understand what you are saying. And also i don't have the money to replace the system so am doing my best to fix it.

2. Kevindgas - Thanks for all your suggestions. However i don't think the system is plumbed as you say. I have drawn a rough picture to show the setup. Also i have already drained the system, and yes it was black. So i refilled with a cleanser and drained again 1 month later. Then i refilled minus inhibitor. This is now as the system stands. Here is the picture.

 

[judderi]

Bump! Anyone?

 

[Nige F]

Gravity circuit should be 28 mm pipe and that combined "overflow" /fill is crap...........fill should go to bottom boiler pipe @ cyl and the "overflow" Vent should come off the top boiler pipe

 

[kevplumb]

Gravity circuit should be 28 mm pipe and that combined "overflow" /fill is rubbish...........fill should go to bottom boiler pipe @ cyl and the "overflow" Vent should come off the top boiler pipe

howay NIGE it worked when i fitted it

 

[holty]

it could be because your primary circuit to the cylinder is gravity hence hot water rises due to less density off colder water ie hot flow at top this then could also mean youve no control telling the boiler to shut off were as a heat leak rad would come in or just a simple cylinder thermostat to tell the boiler to shut off. sounds like hot water when reached to its max temp is not conveying and just boiling

 

[judderi]

So what do you suggest i do to fix the problem?

The boiler itself has an inbuilt thermostat. Its like a thin wire connected to the top of the heat exchanger. This wire then runns down to the thermostat situated next to the timer and controlls.

Even if i was to adapt the pipework for the fill/overflow i would still get the boiling up problem wouldent i?

Or maybe because the fill and overflow are combined i am suffering from an air lock causing the boiling problem?

Where do i go from here guys?

Im still thinking i should swap the hot and cold feed round for the cylinder. Hot water in at the bottom just makes more sense to me.

 

[Gasguru]

You sure pipes to cylinder coil are only 22?

What is the vertical distance from the top of the boiler to the base of the cylinder?

What is the horizontal distance from the boiler to the cylinder?

 

[Nige F]

Listen to me and GasGuru and forget about flow to bottom of coil

 

[judderi]

Im not sure about the pipe being 22mm i will need to measure it.

There is only about 1 meter between the top boiler pipe and the bottom cylinder pipe. They are in line with each other so no distance horizontally.

Oh and i would forget about swithching the feeds if you gave me other ideas to try.

Next question. Might the problem be related to air in the system as the overflow and feed are combined? Could i try cracking open the joint on the bottom boiler pipe and see if air is released?

 

[Nige F]

I`ve run out of ideas