Central heating flowing into expansion tank

[PASUK]

Hello

I have recently moved house and I am discovering some horrors with the central heating system.
I'm skint at the moment after shelling out for the place so doing my best to DIY as much as practically possible.

My knowledge of traditional heating systems is very low, (my last place was a combi boiler system) but what I have noticed is that when the heating is on and the pump is active that a considerable amount of water is being pumped into the expansion tank and this is not good.

I don't have much knowledge about these things but I think the position of the pump is not helping.

Here is a photo taken next to the boiler on the 1st floor...

Pump Positioning

• PASUK
• 13 Feb 2014
• 1

The expansion tank is about 1 - 2 m directly above where this photo is taken in the loft.

What I can tell is that the hw water is coming up from the boiler / tank up through the bottom left into the pump.

The pipe going directly above the pump into the loft via the reducing tee is going into the top of the expansion tank.
The pipe top right is feeding water back from the expansion tank.
The central heating circuit follows the pipe bottom right.

This might be a silly observation but is one big factor that the pump / pipework is positioned incorrectly as the easiest path for most of the pumped water is to go up rather than go around the 180 bend?

My temporary fix has been to turn the pump down to the lowest speed but that only reduces the amount of water flowing into the expansion tank and isn't heating the more remote radiators as effectively as the higher settings.

Is there some sort of valve I can buy that might help or do I need to redo the way this is laid out?

Thanks very much

ps first post on this forum!

 

[twgas]

The pipe on the right should be flow from the boiler, the 22mm pipe from the tee, going up, should be the open vent which should rise 450mm above the f&e tank then bend back down to terminate within the f&e tank above the water line. The 15mm pipe in the tee on the left should be the cold feed which needs to be connected to the tank at low level. The arrow on the pump should point down and into your motorised valve(s).

 

[PASUK]

OK so totally the opposite direction to what I thought!
I have checked the arrow on the pump and yes you are absolutely correct.
I also can see that the pipe rising up and above the expansion tank and back in the top is the 22mm pipe and the cold feed at the bottom of the expansion tank is the 15mm.

Also...
That 22mm pipe going above the expansion tank and back in does indeed raise above the water line by about 450mm.

Expansion Tank

• PASUK
• 13 Feb 2014
• 1

It sounds like the setup at my house is correct!

So why does the heated water overflow into the expansion tank?

Could it be that the pump is simply flowing too fast (even at the slowest setting) and the water rising in the 22mm pipe on the right of my original photo is being carried by the momentum driven by the pump up higher than 450mm above the water line in the expansion tank and flowing over?

If so what is the best solution? Should I raise the pipe higher than 450mm?

Thanks v much

 

[dcawkwell]

The first thing to do would be turn the pump speed down to 1.
Open all the radiator valves at both sides fully.
If still overflowing put a push fit cap end on the expansion pipe over the tank.
The expansion can go back up the feed pipe.

Most likely cause is there is a blockage in the pipework.

Open the drain valve and allow some of the water to flow out as it is replenished by the header tank. That should clean it up a bit and may improve things. Some system cleaner after may help.

 

[Gasguru]

.....If still overflowing put a push fit cap end on the expansion pipe over the tank.
The expansion can go back up the feed pipe.

Hmm, combined feed and vent is not always permitted and it would only be a 15mm pipe.

There's a good chance that the H section pipework above the pump is partially blocked. Cut it out and redo.

 

[Razor900]

If still overflowing put a push fit cap end on the expansion pipe over the tank.
The expansion can go back up the feed pipe.

Unless the feed is blocked then they have created a bomb

The H section needs cutting out and cleaning

 

[Razor900]

Too fast for me Gasguru

 

[CombustionGuy]

Try magnet on the pipework if it sticks it's blocked or full of sludge

 

[twgas]

The first thing to do would be turn the pump speed down to 1.
Open all the radiator valves at both sides fully.
If still overflowing put a push fit cap end on the expansion pipe over the tank.
The expansion can go back up the feed pipe.

Most likely cause is there is a blockage in the pipework.

Open the drain valve and allow some of the water to flow out as it is replenished by the header tank. That should clean it up a bit and may improve things. Some system cleaner after may help.

I cant believe you actually advise capping the open vent.
Most likely cause of pumping over is a restriction/blockage in the pipework in the photo.(between the tees)

 

[GavThePlumber]

Kipper for breakfast? Sounds like he has been smoking kipper, if that what the kids call marijuana these days

 

[dcawkwell]

If still overflowing put a push fit cap end on the expansion pipe over the tank.
The expansion can go back up the feed pipe.

Unless the feed is blocked then they have created a bomb

The H section needs cutting out and cleaning

Or the pressure to clear it.

 

[GavThePlumber]

You can not give advice like that over open forum imo

 

[James1991]

So why does the heated water overflow into the expansion tank?

Like others have stated, you have a blockage where the vent and feed connect to the circulating pipe work . It needs to be cut out and cleaned. By the looks of things, you need to clean the F&E tank out too.

 

[PASUK]

Thanks for all the advice, it's been really helpful.

I now have a separate question to do with the way 22 and 15 mm pipe has been used on my system. To keep it neat I'm going to start a new thread.

Thanks again - great forum!