Bathroom plumbing mods

[scottygio]

Hope you can help with the following plumbing queries:

1) my house originally had a cold water cistern but was ripped out and replaced by a combination boiler to provide heating. After the stopcock I have 22mm copper pipe which originally fed the cistern. Can i reduce this 22mm to 15mm pipe? The 15mm will then supply the rest of the cold water supply i.e. kitchen sink, combination boiler, bathroom sink, wc cistern, shower. As you know baths are 22mm so that would mean changing from a 15mm to a 22mm just below the bath. Would that be okay? Everything mentioned above will be under rising mains pressure.

2) because of building regs I have to install an air admittance valve (durgo) in my bathroom. What is the minimum height i can install this. Does it just have to be above the outlet of the wc ( which is quite low anyway)

3) I have a combination boiler and can't seem to find a drain valve. My boiler is on the bottom floor. Would it be possible that the installers never put in a drain valve? Or can the drain valve be in the boiler itself? If i were to put in a drain valve does it have to be at the lowest point of the sealed system? This would be under the floorboards which would mean if i fixed a hose to it the water would only drain out all the water above the outlet of the hose and leave all the water below the outlet of the hose still in the sealed system. Is this right?

sorry for being longwinded but so much to ask

thanks in advance

 

[maka2k2]

cold to your bath will already be 15mm

durgo valve has to be higher than cistern pan doesnt it?

just put a drain off cock on one of the radiators it will be fine.

i see on some new propertys i have been working at the installers have drilled a hole through to the outside of the house(below floor level), and put a drain off cock tight up to the brick work so its less messy..good idea if you ask me

 

[Bahco]

You can change to 15 mm if you want to (and you have adequate water pressure) but can't see how you will benefit.

You should have a vented stack already on your property so you should not need a durgo unless it is an additional toilet.

You need to have a drain off at the lowest point or as you rightly suspect, not all the water will drain off if the drain valve is higher than some of the pipework.

 

[ChrisR]

Cold to your bath will NOT be 15mm if it was fed from the cistern.

Why replace cold water pipes with smaller ones? Feed to the combi is best left big.


HW pipes from the combi are better in 15mm or you wait longer and lose more heat.

What's the combi?

Yes you should have a drain point or two (one each side is best) low down. If you haven't, the installers are very unlikely to have flushed it properly, as they couldn't drain the initial fill, with flux residues etc.


HTH:
stub stack

 

[scottygio]

My feed to the combi is 15mm.
I'm a little tight for space and converting from 22mm to 15mm would give me that space. My only concern is the flow of water to the bath as this would be a 15mm to 22mm upgrade in pipe.
The boiler is a ferroli optima 701.I can't find a drain valve but the boiler is fitted to an outside wall and there is a 15mm pipe coming from the boiler and hang ing at the wall. is this the overflow. I have also found a stopcock betweem the flow and return of the sealed system. why is this?

thanks again fo the input

scott

 

[Gasman1015]

Overflow pipe is the expansion relief valve outlet.

Stopcock is a manual bypass valve.

 

[scottygio]

what is the purpose of the manual bypass valve?

 

[bster]

Dergo\ air admittance valve should be higher then the highest trap it serves.