Hot Water pressure seems low

Blasphemous · 2 Oct 2006

Hello all,

First some back ground to my problem:

Marathon Floor standing Boiler.
Feed & Expansion tank in loft.
Hot water storage cylinder in cupboard (on upstairs landing).
Cannot see a Pump and/or diverter valve anywhere so I assume this is a Gravity fed system?
Central Heating is 8mm Minibore with Manifolds etc.

Anyway, I've just moved a radiator in one of the bedrooms. To do this I used a set of 'Header Tank Bungs' and plugged the Feed & Expansion tank Cold feed and Expansion pipe.

I cut into the pipework 'one pipe at a time' to avoid an 'Unexpected' drain down! After re-routing the pipework and mounting a new radiator, I took out the 'Bungs'. Then I opened the new radiator valves and the system began to pressurise. I then opened the bleed nipple until fully pressurised.

So everything was fine... until later that day when my wife went to run a bath and said 'The Hot Water pressure used to be better than that'! I checked the flow rate on the bath and other hot water taps in the house and the flow rate is definitely slower than before.

Any ideas? I'd appreciate your advice.

Thanks.

Gasguru · 2 Oct 2006

The boiler pump is probably within the boiler casing (normally sits in front of the heat exchanger).

Hot water tap pressure should not have anything to do with your heating modifications unless you have turned off the cold feed to the hot water cylinder.

This may then have introduced an air lock.

So were any other valves closed off?

Blasphemous · 2 Oct 2006

Nope, no valves turned off. As I said, the only thing I did was 'Bung' the Feed & Expansion pipes in the Feed and Expansion Tank.

Its got me baffled!

Gasguru · 2 Oct 2006

Ok did you tie up the float valve in the F/E tank or shut off the mains?

If you shut the mains is there any chance you (or your wife) drained down the cold tank and introduced an air lock?

Blasphemous · 2 Oct 2006

Thanks for your reply's Gasguru.

No, I didn't tie up the ball cock. I knew the Bungs would provide a vacuum and thus allow me to cut into 'one section of pipe at a time'.

Its an absolute mystery!

My background is Engineering (Fitter) and then Building/Plumbing for 8 years. Last year I did my ACS. So its not like I don't have a clue but I've never come across this before

As a side note, as I say I did my ACS last year but i'm not working. I left work about 2 years ago to look after my son but I'm hopefully going to get back to work this year..Please God!!!

I'm beginning to think the pressure drop is totally unrelated. The pressure isn't really bad but its noticibly dropped from what it was previous.

Any other ideas?

Blasphemous · 2 Oct 2006

Sorry Gasguru, No I didn't shut off the Mains either.

Gasguru · 2 Oct 2006

Bet your wifes happy - plumber can't fix his own system

Could be right just coincidence. Assume airlocked and do as usual to clear.

Blasphemous · 2 Oct 2006

Cheers Gasguru,

I've been out of the building/plumbing game for over 8 years so I probably know about as much as what you will have forgot this morning... in other words very little!

What would be 'normal' proceedure in this case?

Thanks once more for your advice on all of this.

Blasphemous · 2 Oct 2006

Sorry again Gasguru,

Do you mean:

Connect the Cold Water mains to a Hot Water pipe and force air lock out using Cold Water mains pressure?

Thanks

Gasguru · 2 Oct 2006

Works for me - sometimes you need to drag a hose up to the cold tank and blast the air through.

Blasphemous · 2 Oct 2006

Cheers Gasguru. I'll give it a whirl tomorrow.

In the 'old days' if there was a washing machine with Hot & Cold feed we used to disconnect the washing machine and connect a 'washing machine hose' between the cold and hot then open the Hot then the cold main for about 30 seconds or so to drive an air lock back up into the tank. Is this still the method or have things moved on since I was a lad

I might need to do a refresher course before I go into the game again!

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Hot Water pressure seems low

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