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I have been having problems getting my system to heat the water up on my gas fired central heating system.
I have an open vented system, with hot water tank (not a Combi).
We have a control panel that allows the system to be, OFF completely, ON water only or ON Water and Heating with timer attached.
The feed into the hot water tank gets scoldingly hot, but the return out is cold, this is very close to the cold feed from the feeder, expansion tank.
I have drained the system down, put a cleaner through the system and flushed out all the pipes.
This afternoon after completing the flush and bleeding the air out of the system, ensuring that all the radiators worked, the return from the hot water tank got warmer than it had been, when the system was set to ON water only, when I set it to ON Water and Heating and switched every radiator off individually the return from the hot water tank got really hot,this is what I believe it should be like when it is ON Water only.

Any ideas as to whether this is how it should be?
Or is there a problem with my control panel or motorised valve attached?

Is this new problem, i.e the system used to work correctly?

Yes Atticus, this is new

The boiler got changed a month or so ago, only the boiler, with a filter added and we have had one or two problems which I have argued with the installers about, but time goes on and I need to solve the problem,

To confuse things further, my success of the other day of getting the water to heat up with the settings at ON water and heating, with all radiators switched off has now went back to being just mildly warm

The system also pulls a lot of air, which has to be bled off constantly from the filter.
The filter has plastic corner joints leading into and out of it and when working with the filter, either isolating to clean or bleeding air, it swivels and moves constantly on these corner joints.

Seems un-natural to me

Didn't the installer flush the system before fitting the new boiler? If not, he's a cowboy - which might explain the problems you are having.

Which filter do you have?

Can you post some pics of your system? An overall view is better than close-ups of each component - need to see how it's joined together.

Hi,

Yes they cleaned the system, but I was becoming paranoid because of the arguments I was having with them, so I cleaned it again.
The filter is an Adey Magna Clean Professional
The Hot water tank is in the upper level of the airing cupboard up stairs almost directly above the bolier
The pump and motorised valve are in the lower level of the airing cupboard up stairs.
The filter and the boiler are downstair filter to the right of the Boiler (Seperate cupboards)

I'm sorry to say this, but that looks a very second rate job. Plastic connectors - ugh!

Are those two plastic pipes I can see on the left of the pump pic? If so, what do they connect to?

Is the motorized valve a 2-port (in and out) or a three port (in and two outs)? If two port, you should have two! The valve make and number would be helpful.

How everything has been connected together is confusing as it's spread-out. Could you post a drawing showing how the main components (boiler, filter, cylinder, pump, motorized valve) are connected together?

Is the control panel a new one or was it a left-over from the old boiler?

Atticus Finch wrote:I'm sorry to say this, but that looks a very second rate job.

I agree, pipe diameters are wrong and what are all the service valves for???

plumbbob wrote:Pipe diameters are wrong and what are all the service valves for???

I have a suspicion that it is a gravity HW/pumped CH system which has not been converted to fully pumped (as required by Building Regulations) when the new boiler was installed. That would explain what looks like a single zone valve.

Hi,
Attached drawing of the system layout as best as I can get, hope you can understand it
The motorised valve is 2 port on the feed to the radiators, it is a Honeywell, cant identify model
I have indicated the two plastic pipes on drawing, they were there, not put in by the boiler installer
Air certainly seems to be a problem, which it wasn't before.

I think AF is right, the system is a dodgy DIY conversion from a gravity system to fully pumped.

I am not surprised it is pulling in air because the two connections to the expansion tank are wrongly on different sides of the pump.

There are only two standard types of plumbing arrangements. These are referred to as Sundial "S" plan and Sundial "Y" plan. These use 2 x 2 port valves or 1 x 3 port valve respectively. For most small to medium sized domestic dwelling, the "Y" plan is by far the most common an efficient. Google these for a schematic.

An interesting question but why did you opt for a new system boiler (traditional boiler) rather than a combination boiler? I would have expected the installation engineer to point out the shortcomings of your existing pipework during the initial survey. He must have known the new boiler might have issues and that would reflect on his reputation.

plumbbob wrote:I am not surprised it is pulling in air because the two connections to the expansion tank are wrongly on different sides of the pump.

Having the vent and feed on opposite sides of the boiler was fairly normal with cast iron HE's as the pressure drop through the boiler was negligible. The pressure drop across modern Ali and SS HE's is much greater, so the feed and vent pipes have to be on the same side, normally just before the pump.

As well as moving the feed pipe connection, a second motorized valve is required in the HW circuit and a cylinder stat. In addition a new programmer is probably required so you have independent control of CH/HW times and temperatures. I have shown the changes in this diagram. And get rid of the plastic pipes/joints.

Atticus Finch wrote:Having the vent and feed on opposite sides of the boiler was fairly normal with cast iron HE's as the pressure drop through the boiler was negligible.

That may well be the case although I have never followed that practice because it has been a constant irritation to me over the years, to go into house after house and finding hot expansion tanks or half filled radiators full of black sludge.

There has been a handy device on the market for decades which stops this happening and removes trapped air to boot. With careful planning though, the same can achieved without this device. I have never found a reason to build in what at best could be a potential problem.

Atticus Finch wrote:As well as moving the feed pipe connection, a second motorized valve is required in the HW circuit and a cylinder stat. In addition a new programmer is probably required so you have independent control of CH/HW times and temperatures. I have shown the changes in this diagram. And get rid of the plastic pipes/joints.

Agreed, except I would prefer that "Y" plan as it removes any necessity of a bypass which improves the flow to the radiators.

Oh, and get rid of those service valves. They may actually be the main current cause of your problem.

Thanks guys, a lot to ponder
Then to find someone competant to carry it out