Confused By Hot Water Tank Plumbing

[ProDave]

I have an immersion heater to replace tomorrow and I'm not understanding the plumbing.

It's a conventional foam lagged hot water tank, direct heated by a single immersion heater. Fed from a cold header tank in the loft.

Problem #1, no drain valve fitted. That makes things a little awkward.

But while looking around the tank, something struck me as odd about the way it's plumbed, so I will try and describe it.

First the bits I understand:

From the top of the tank a 22mm pipe goes straight up into the loft, so this will be the expansion pipe. Teed off from that is a 22mm pipe going down through the floor, so that will be the hot water draw off.

At the back of the tank near the floor is a port in the side of the tank. From here a pipe goes up into the loft via a gate valve, so that's the cold feed into the tank.

NOW it gets "confusing"

Also teed off from that cold feed in port, is a 22mm pipe going down through the floor. What's that then? Perhaps it's a tank fed cold feed to the bath? If so that's a bit naughty having it fed directly from the cold in port, but if so that might be my get out to enable me to drain the tank in the absence of a drain point.

Then it gets even more confusing.

Near the top there's a third port in the tank, with another 22mm pipe going down through the floor. What's that for?

I'm told the tank is only heated by the immersion heater.

 

[NozSpark]

Do they have a boost pump somewhere for a shower?

 

[Rob_the_rich]

I have an immersion heater to replace tomorrow and I'm not understanding the plumbing.

It's a conventional foam lagged hot water tank, direct heated by a single immersion heater. Fed from a cold header tank in the loft.

Problem #1, no drain valve fitted. That makes things a little awkward.

But while looking around the tank, something struck me as odd about the way it's plumbed, so I will try and describe it.

First the bits I understand:

From the top of the tank a 22mm pipe goes straight up into the loft, so this will be the expansion pipe. Teed off from that is a 22mm pipe going down through the floor, so that will be the hot water draw off.

At the back of the tank near the floor is a port in the side of the tank. From here a pipe goes up into the loft via a gate valve, so that's the cold feed into the tank.

NOW it gets "confusing"

Also teed off from that cold feed in port, is a 22mm pipe going down through the floor. What's that then? Perhaps it's a tank fed cold feed to the bath? If so that's a bit naughty having it fed directly from the cold in port, but if so that might be my get out to enable me to drain the tank in the absence of a drain point.

Then it gets even more confusing.

Near the top there's a third port in the tank, with another 22mm pipe going down through the floor. What's that for?

I'm told the tank is only heated by the immersion heater.

sounds like the cold and hot going through the floor are for a shower? or second bathroom? And yes, it is a bit naughty taking the cold from the HW feed, but there you go, it is an ill wind.. etc.

 

[kerching]

Sounds like an attempt at a "balanced feed" for a shower!...but I am NO Plumbit!

But what do I know?....by todays standards i am probably not even an electrician any more

 

[ProDave]

I'll find out more tomorrow.

What worries me, is a plumber looked at it first and said "you need an electrician". He probably clocked the lack of drain valve and thought too much trouble.

 

[Andy™]

if youre confused by a few pipes, then there is no hope for us all. especially plumbers