Central heating water/domestic water mixed

[-AndyH-]

Hi

We've got a DIY man in at the moment who's fitting a new bathroom and he has unfortuantely caused a problem with our central heating/domestic water.

Basically our system is slightly complicated (because of the size of our house). We have two Vaillant VC GB 242 EH system boilers, both joined together, that purely heat the central heating downstairs/upstairs in our house (35mm copper piping). Our domestic hot water is heating by a 400 litre Everhot mains pressured cyclinder that runs on Economy 7. In order to fill our central heating system, there is a 15mm filling loop on the mains entering the Everhot cyclinder at the bottom connected to a flexible pipe with an isolation valve and a non-return valve.

The DIY guy was removing some of the bathroom fittings (shower/bath etc.) and we think that he turned off the cold water mains supply to the house, closed the stop cock to the Everhot cylinder (which is after the tee off to the central heating fill pipe), BUT opened the isolation valve by mistake.

The hot/cold water smelt funny and was a browny colour (central heating water) this morning so I go a plumber in to have a look. He quickly realised what was happening when the central heating pump was running dry and hot water was flowing through the cold water pipes in our house even though he turned off the mains supply to the house. The non-return valve was not working!

He has recommened running the cold water taps for 12hrs to clean them out, but I'm concerned that there were a load of inhibitor chemicals recently added to the central heating and these have ended up in the cylinder (domestic hot water). I have done a test with our swimming pool (chlorine/bromine/alkainity/pH) test kit on the hot cold water and the cold water appears normal (only useful reading is the pH at 7.2) but the hot water is 6.8.

Any ideas what to do?

Thanks

 

[breezer]

would not

running the cold water taps for 12hrs to clean them out

 

[sm1thson]

We've got a DIY man in

-is that not a contridiction of terms?

anyway, Im not a plumber or anything, but i would run the taps to get the inhabitor out and then think about getting the inhabitor in the heating topped up!

 

[-AndyH-]

Any ideas how long I should run for?

We have four bathrooms upstairs/one toilet downstairs/three kitchen and utility sinks downstairs (the two kitchen cold water taps run directly off the water mains as the rest of the water goes through a Waterside water softener before being distributed around the house)

 

[Onetap]

Any ideas what to do?

Thanks

Let me think.

It's a big house that needs two boilers, with a 400 litre unvented hot water storage system, 4 bathrooms upstairs and a swimming pool?

Could I suggest that next time you pay for someone competent and then you might not have to seek free advice here?


Having said that;



I'd suggest drain, refill, drain, refill, drain & refill. Anything remaining should be too diluted to pose any risk & will get further diluted as water is used. I'm not a chemist, though. Get COSHH data sheets from the inhibitor manufacturer's website or ring them on Monday to ask advice. Sounds like there was a corrosion problem.

 

[JohnD]

"It is the business of the wealthy man
To give employment to the Artisan"

 

[-AndyH-]

I have had a bit of a nightmare with plumbers recently.

I guess it's like all professions, sometimes it can be hard to get the right guy for the right job.

This morning I called a plumber, recommended to me by a couple of friends. I said to him that I thought the central heating/domestic waters were intermixed. Earliest he could come out was 7 December. Not much use for any household with potentially toxic domestic water.

A couple of months back, one of our boilers had an intermittent fault where the flame reset switch would pop out. It was happening from every few hours to a couple of days. I get a plumber out (Corgi registered) and he strips the boilers/cleans it etc. but doesn't fix the problem. He then starts replacing parts and a few weeks later I have a £1,000 bill and a boiler that has completely stopped working. He wouldn't guarantee he could fix the boiler for a set price, but he wanted to replace three PCBs at £100 each (parts only). I eventually get a BG engineer out for a set charge who got the boiler up and running again and it appeared to be working ok. However, the flame reset switch problem has started again.

The conculsion of this all, if anyone can recommend me a decent plumber in my area then I'm all ears (I want to replace the Economy 7 cylinder with a Meglaflo and use the boilers to heat the domestic hot water). From what I can see there are quite a few knowledgable ones on here

 

[Onetap]

Not much use for any household with potentially toxic domestic water.

It's very unlikely that the inhibitors would be a health risk; the coils in indirect cylinders often leak, causing the CH water to enter the domestic hot water system, so nothing very toxic could be in the mixture. I've also heard stories of people drawing water from heating systems; it can turn your whites an unattractive shade of brown, apparently.

If the boilers are open vented (it sounds like it), then they should not be supplied from the softened water supply

 

[-AndyH-]

Onetap - Thanks for your response. Excuse my ignorance, but why should the central heating system not be filled up with softened water?

The house I live in is circa 10 years old. It was setup so all the water was softened, except the drinking cold water taps in the kitchen.

 

[BoxBasher]

The non-return valve was not working!

Thats why the filling loop should ALWAYS be physically disconnected unless actually filling the system.

Lesson to be learnt by anybody who doesn't already do it...

 

[Onetap]

If the boilers are open vented (it sounds like it)......

Whoops Sealed system.

It still sounds like it's fed from the softened water supply. The CH inhibitors are formulated for use with hard water or naturally soft water (which is not the same as softened water). The manufacturers' instructions probably advise against using softened water. You should use mains water, or de-ionized water on large systems.

Softened water is more corrosive, but the quantities of the dissolved solids involved are so small (300mg/litre?) that it probably wouldn't be a problem unless there was a long term problem with the system, like a leak.

 

[Nige F]

"It is the business of the wealthy man
To give employment to the Artisan"

All things bright + Beautiful The rich man in his castle. The Poor man @ his gate ........God sees them ....and orders their estate...........Just waiting for the Revolution

 

[JohnD]

Lord Finchley tried to mend the Electric Light

Himself. It struck him dead: And serve him right!

It is the business of the wealthy man

To give employment to the artisan.


Lord Finchley, by Hilaire Beloc