Using the redundant feed to the cylinder coil when fitting a combi.

[Dannypipe]

Hi all.

I've done something I don't do much of today. Fitted a combination boiler.

I tend to fit system and HO boilers. To give you an idea, the last combi I fitted was during the scrappage scheme.

My question is:

Does anyone use the redundant flow to the cylinder coil to knit into the old hot outlet from the cylinder?

I've had a hell of a day, up in the loft, running the new 15mm feed through to the airing cupboard. (The loft was stuffed with junk).

When I was a lad, I worked with an engineer who did utilise the redundant flow to the coil, infact he got me to knit that in why he plumbed in the boiler. Anyway, my father (who this engineer worked for at the time) got it in the neck as the ho****er was running a bit black (not suprising considering the state of most primary water).

Is this common practise? I could have saved myself a good bit of time, and a few lengths of copper today, but wanted it all new.

Any replies gratefully received.

Danny

 

[bennygas]

alright danny? just a question to make sure im understanding you right, but if you've taken a cylinder out, and are fitting a combi in lieu, why would you not use the existing hot supply rather than the redundant primary flow? the primary side is likely full of all manner of contaminants, could be larger bore than the hot (and hence increases draw off before hot water delivery), and goes to places other than the hot taps. if the hot supply's right there? are my wires crossed? wouldn't be the first time...

 

[bennygas]

hang on - boiler's not going where the cylinder is, is that right? boiler back in the same place, cylinder out?

 

[hammers4spanner]

as benny gas says!!

 

[Dannypipe]

Right, to explain.

The the boiler is in a location remote from any other hot outlets that I could use. The cylinder is a good distance from the boiler, but I have a redundant pipe from the 3 port valve at the boiler to the hot water cylinder. I will have to take the new DHW supply to either a hot outlet, or to the old cylinder outlet to liven the system up with hot water.

Once when I was about 20, I worked for a day with a bloke who got me to do as above. It goes against the grain for me, but if its common practise I would like to know!

As I've said, combi's are not my bread and butter work. Mostly bigger properties and systems.

 

[Dannypipe]

Hope that's making it clear. Its not a hard concept to understand, but maybe hard to explain!

 

[AWheating]

contamination and waste of water being the two reason i can see it should not be done.

also leaded solder on the heating pipework?? who knows.

 

[hammers4spanner]

As bennygas says maybe not a wise idea to use a heating pipe for a domestic draw off , i know maybe a pain but imo i would run a dhw to nearest source ( plus get flow rate correct)

 

[mcniven]

Iv done this before so that the customer did not have to lift flooring as the feed from old F&E tank we tied into the main in loft which worked as a main to the combi (system to combi same location)

 

[bennygas]

so you want to know if it's ok to re-purpose the old flow pipe that went from the old boiler up to the y-plan to convey hot water into the existing hot water circuit by joining on at the new boiler and in the airing cupboard. well, in a word, no. I haven't and wouldn't, but I dare say it goes on. The only problem is, you gotta pick up the hot and cold for the new boiler from somewhere, and ideally without taking too much of a hit on pressure and flow rate or giving the custard a massive great dead leg when theyturn the tap on. it can be a nightmare, we've all been there mate.

 

[Dannypipe]

Yeah, I agree with you. Which is why I did it properly today...which is why I'm still itching even after a shower and a bath!!

It just popped into my mind what this bloke did. In fairness, he did get fired eventually by my father. I think he fitted a boiler and it was hanging off the wall.

I just wanted some opinions, as it could clearly of saved me some aggro' today!!

 

[Dannypipe]

so you want to know if it's ok to re-purpose the old flow pipe that went from the old boiler up to the y-plan to convey hot water into the existing hot water circuit by joining on at the new boiler and in the airing cupboard.

In a word, yes. That is exactly the question I was asking. Thanks!

 

[Dannypipe]

In this instance, the nearest hot water draw off was via the old cylinder.

I went with my gut and did the right thing. I wouldn't want to have my hot water supplied through a cruddy old feed to a coil (even if it was 15mm as in this instance!!).

However it stuck in my mind that this fella did it, and he was ribbing me at the time as I was saying we should run a new feed to the bath.

Bare in mind this was back in my early twenties and I'm now mid thirties, so maybe it was acceptable 13 odd years back??

 

[Whn1]

I've seen a couple of people do this but for a gas run, going back sometime mind.

 

[Dannypipe]

I'm sure that it gets done. I just didn't want to miss a trick if everyone did it, so would I......talk about being a sheep!!!!

I like to do things properly and as tempted as I was to thread a bit of plastic through that loft today, I did it in tube.

The loft was one of those that you pop the hatch and just sigh. Two massive redundant CWS tanks, galvanised, full of crap. And barely a spare inch of space.

When I priced it up, I asked is the loft fairly clear, and was told it was. I was swearing quite a bit today as you can imagine. At one point I was lieing on my belly across a few joists to sweat an elbow, up to my ears in insulation and thinking, why didn't I become a banker/footballer/night club owner?

 

[Dannypipe]

Oh yeah, because I'm crap at maths, crap at football and skint!!

 

[hammers4spanner]

All been there fella !!
Spent years doing installs pack a day etc all that malarky rush and tear in council houses

Everyday i wish done something else then speak to someone who is an accountant and they say wish they became a plumber !!

 

[bennygas]

join the club, but i'm effin butt ugly too :ears:

 

[mcniven]

hahaha benny

 

[AWheating]

i wanted to be an underwear model................but i didnt have the balls for it!!

to shy

 

[bennygas]

i wanted to be chiropractor but I don't know enough about egypt.

 

[Whn1]

i wanted to be chiropractor but I don't know enough about egypt.

Ohh that's good!


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[ambrosia]

talking of dead legs on hot water pipes, doc L says you have to have lagging a meter from the boiler,
I almost never do installs so not guilty on this one, but nobody seems to do it

 

[bennygas]

i remember there being something in doc l to do with lagging within 1 metre of the cylinder, but didn't realise about the boiler. news to me.

 

[ambrosia]

dam am i remembering it wrong, college days and doc L is becoming a bit blury

there are parts of doc L which did seem stupid to me, i often get call outs to tenants who think their heating is broken when they simply cant use the contols. a non doc L compliant programmer would have been far more suitable in those cases. But hey what can you do but charge the landlords for the call out