Corrosion?

[joeirish]

Folks

 

I took a good look at my four year old ufh manifold today because one of the accentuators was sticking. I discovered that the pin that opens and closes the valve had stuck and there was a bit of rust around it. I got it sorted with some WD40 and a bit of judicious tapping with a hammer and it seems to fully work again.

 

I then noticed the gauges (?) that show the rate of flow and all that are in use had rusty coloured water in them. I attach a photo. Different circuits are different shades of brown. One gauge is still the original clear colour but this circuit is not connected (3rd from the right in the photo). The water is heated via an oil boiler. Should I be concerned and should I do something such as have the entire system flushed out and the fluid replaced? Thanks

[PeterW]

Looks like there was no inhibitor in the system ..?? Is it an open tank or a sealed system..?? 

[ProDave]

I shall watch this with interest.

 

I too have discolouration of the water in my UFH manifold flow meters (very similar manifold to above)

 

But in my case it is an ASHP, so in that the water just passes through a stainless steel plate heat exchanger.  All pipework is copper.  HW cylinder is stainless steel.  Heating is Pex Al Pex under floor heating pipe.  Just about the only thing in my system that is ferrous metal is a Grundfoss circulating pump.  And I have 25% antifreeze / inhibitor.  So I am at a loss in my case to know what is discolouring my water.

[joeirish]

Hi Peter

 

Inhibitor was used when it was first commissioned. It is a sealed system as far as I know. But it is a strange set up as I've posted here previously. The fluid is heated by both the boiler and the thermal store. The circuit from the boiler to the thermal store has the ufh cirucits connected to it.

[joeirish]

I just remembered that the pressure dropped a few times and I had to open a feeder valve (sorry about my lack of plumbing knowledge!) to raise it again. It hovers around 1 bar. Not sure if that says anything to help.

[joeirish]

So do I need to flush out the system or is it OK just to leave it as it is Thanks

[Conor]

20 hours ago, joeirish said:

I just remembered that the pressure dropped a few times and I had to open a feeder valve (sorry about my lack of plumbing knowledge!) to raise it again. It hovers around 1 bar. Not sure if that says anything to help.

 

That could introduce enough oxygenated water to cause corrosion. I'd suspect it's your oil boiler doing the damage. How old is it? Do you have a backboiler on a stove or anything?

 

5 hours ago, joeirish said:

So do I need to flush out the system or is it OK just to leave it as it is Thanks

 

For the sake of £20 for inhibitor, I would. Not sure how yours is setup, but you should be able to flush using the filling loop and a hose attached to the drain valve.

[joeirish]

Hi Conor

 

Thanks for the suggestions. The boiler is also only four years old the entire system was installed when the house was built in 2015. I've no problem flushing the system and adding inhibitor but I think it is under some pressure so not sure if I can just do it with a filling loop as you suggest. How would that work? Thanks

[Conor]

The filling loop is connected to your cold mains supply that will pressurise the system to at least 1.5bar... but you only need 1 bar when cold. 

 

Connect hose to the drain valve (should be at bottom of boiler). Open valve. Water will start to drain. Open the fill loop valve. This will start flushing out. You'll need to open and close each UFH loop to ensure everything is flushed. This bit I'm not so sure on as I've only ever done this with a radiator system which is pretty easy.

[joeirish]

Thanks again. I might try a local plumber and see if he can do this. A bit beyond my abilities!!

[Ed Davies]

Do unvented systems have a vent? E.g., one at the top of the system you can open manually when draining and filling? More than one if there's more than one high point?

[Conor]

1 minute ago, Ed Davies said:

Do unvented systems have a vent? E.g., one at the top of the system you can open manually when draining and filling? More than one if there's more than one high point?

 

Yes. And if my Worcester combi boiler is anything to go by, nigh on impossible to access and open. In our system with rads, I just opened bleed valve in the main bathroom towel rail which is the highest point in the system. 

[Temp]

In case not obvious, don't just put  a 500ml bottle of inhibitor in. Calculate how much you need to achieve the recommended concentration. For Furnox F1 they recommend 0.5%. So for example on a 500L thermal store that could be 2.5L (FIVE 500ml bottles) depending on how the store is designed. Plus some for the water in the UFH pipes. 

 

 

[Dreadnaught]

On 20/08/2019 at 19:27, ProDave said:

I too have discolouration of the water in my UFH manifold flow meters

 

@ProDave, did you ever get to the bottom of this?

 

I am currently mulling what additives I will need to add to my heating circuit, if any, when I set it all up.