Coolant in domestic (hot) water supply?

[Rewilding]

Morning, a riddle for you all.

Symptoms;

- Pump running intermittently (every ~30seconds), but no evidence of a leak so far (checked all joints). (I also first replaced the pump and the issue has remained, so I've ruled pump failure out).

- Engine coolant is mysteriously overfull (has not been touched since I flushed and refilled before winter, and has been at a good level until now).

- Taste of antifreeze when showering.

These issues all arose in the same week - is there any connection? My current theory is a failure in the coil connected to the engine in the calorifier. This is causing the pump to run, pushing water into the engine cooling loop, and simultaneously leaking engine coolant into domestic supply.

Given the cost and contortion required to fit a new calorifier, are there any more tests I can try to confirm? Or has anyone got another solution?

 

Many thanks,

Andrew

 

 

[mross]

I agree with your analysis.  Don't drink the hot water - it's slightly toxic now.  If you take the 'radiator cap' off and make the pump run continuously, by opening a tap slightly, can you see the level rise?  If you have a leaking coil, it's probably just a pinhole at the moment, but it won't get any better and is a warning that you will have to take action very soon.

Edited May 16, 2017 by mross

[Rewilding]

I will try as you say with the radiator cap off.

I can make sense of how the pressure in the domestic system would push water into the engine loop (if there is a hole), what I can't make sense of is how the coolant would get back into the cauliflower - i.e. if the pressure is constantly pushing water into the engine loop, how would anything flow the other way?

[WotEver]

10 minutes ago, Rewilding said:

I will try as you say with the radiator cap off.

I can make sense of how the pressure in the domestic system would push water into the engine loop (if there is a hole), what I can't make sense of is how the coolant would get back into the cauliflower - i.e. if the pressure is constantly pushing water into the engine loop, how would anything flow the other way?

When it cools it contracts and creates a low pressure which will pull the coolant through a pin hole. 

[mross]

And when the engine is hot its cooling system is pressurised (a bit).

[WotEver]

1 minute ago, mross said:

And when the engine is hot its cooling system is pressurised (a bit).

Actually, that's probably more likely than my cooling tank scenario. 

Edited May 16, 2017 by WotEver

[mross]

7 minutes ago, mross said:

And when the engine is hot its cooling system is pressurised (a bit).

It's probably both (at separate times).  

[Rewilding]

Ok, thanks. So it seems this could be a reasonable diagnosis then.

I'll investigate further, thanks for your help!

 

[Chewbacka]

If you really want to check for leaks I would disconnect the calorifier coil, blow the water out of the coil then cap off one end and then tee off the other end with a pressure gauge, and pressurise the coil closing a ball valve to seal the coil and then look to see how quickly the pressure decays.  Air will certainly leak out faster than water, so if a leak the pressure should fall fairly quickly.  

Added - I reckon that this will confirm what your already suspect...........

Added - You can pressurise it with your water pump which will give a mixture of water and air in the coil, or you could bodge some fittings and use a tire pump.

Edited May 16, 2017 by Chewbacka