Cleaning out heat exchanger - contaminating water?

[Mr. Clueless]

I don't want this question to get lost within the thread of my boiler/water running hot-cold-hot-cold since it's pretty important, or at least to us it is.

For those who helped out, the chap came out today, has scheduled us for powerflushing & a magnetic filter install as suggested in the other thread.

Today though he checked out the heat exchanger & showed me it being full of rusty crap. He used some acid drain cleaner to clean it out which freed up a lot of the crap in it & said this should allow us to have consistently hot water until he's back out in a couple weeks to do the whole system.

My concern is that it's had acid based drain cleaner running through this heat exchanger that water passes through - and whether this will get traces into the water system (tap water) and whether (stupid question maybe) the tap water system is separate from the central heating water system?



Reason i'm asking is because we keep fish & today would be water change day. Obviously i don't want to change the water if the new water will have traces of drain cleaner in.

A seller we deal with had a connection in water treatment. Around winter time a lot of his customers were commenting of their fish dying all at once, yet the aquarium water tests brought back normal results & they couldn't understand it ... yet when posting in the group they were all from around the same area-ish. His connection in water treatment said how the water system gets additive/s, i guess to stop freezing. The aquarium tests don't pick these up but it's obviously enough to kill the fish off.

So you can see why i'm wanting to avoid it.

So will it not get in the system at all? Should i run the hot tap for [insert time length here]? He did flush the exchanger out before fitting it but i don't want to take the chance.

 

[nortonj]

Its totally seperate. The water is heated by seperate layers of plates. One full of central heating water and one full of clean tap water this is replicated a few times over and the plates sandwiched together to transfer the heat.

 

[Mr. Clueless]

Aye that's pretty much what he said. I must have a misunderstanding of it then?

As he took it off there were 4 holes. 2 were shiny silver & 2 were black, which he said shouldn't be the case & will be because of the rust etc.

He poured the acid cleaner into the holes & let it sit for 5-10 mins. Poured away, rinsed & repeated.

What i was thinking is if water enters through one side & out the other & gets heated along the way then it'll be taking the same path as the acid cleaner did? So if the acid cleaner is only say 98% out of there then it'll be getting in the system, be it tap water system or central heating system or both?

He never said anything about it & based also on your reply i'm sure i must have a misunderstanding somewhere coupled with worry that i don't want to end up killing our fish off.

 

[Brigadier]

Logically, if it went through the CH side, it'll be circulating in the CH side (i.e. going around your rads, and not out of your taps).
And, if it went through the HW side, run the hot tap for a few minutes, and it will all be gone anyway.

Finally, you don't treat your fish to hot water anyway, do you? The cold tap water comes straight from the mains anyway, so doesn't go through the boiler.

 

[Mr. Clueless]

Finally, you don't treat your fish to hot water anyway, do you? The cold tap water comes straight from the mains anyway, so doesn't go through the boiler.

Not 'hot' water no, but they're not cold water fish, they're tropical so the hot tap gets run & then use the cold to bring it down to about 26c-27c, treat with conditioner & then it's good to go in the tank.

 

[Brigadier]

Running the tap beforehand then will flush anything out, if it was even there.

 

[Brigadier]

Would it not be better to boil cold water in a kettle, then blend it down to the required temperature with cold, rather than use "hot tap" water?

After all, I definitely would not fill a kettle from the hot tap, to make a brew, so I doubt it is as good for the fish as warmed-up mains water.

 

[Mr. Clueless]

Would it not be better to boil cold water in a kettle, then blend it down to the required temperature with cold, rather than use "hot tap" water?

After all, I definitely would not fill a kettle from the hot tap, to make a brew, so I doubt it is as good for the fish as warmed-up mains water.

To be perfectly honest i don't know. My wife is more in to this than i am and even with that we've only been keeping them for 12 months & consult groups for questions answered. I'll have to ask about that & see what other more experienced people do. I know some use RO water which i guess they must just heat up in a pan maybe. I'll have to ask.


When he was working on the boiler he had the bathroom sink tap running when testing.

I ran the downstairs tap now & it was coughing & spluttering but sorted itself out after a bit.

Came upstairs & bath tap was ok.

Turned bathroom sink tap on & it spat a load of black crap out & then a few more bits for a while before finally running clear. Any idea why that'd be?

 

[Nige F]

After all, I definitely would not fill a kettle from the hot tap, to make a brew, .

You're right there Brigadier. An abiding memory is my old dad using the hot tap - because the fire was burning anyway, heating the water - it was gross.