Thermostaticaly controlled mixer shower + angry wife!

[JohnD]

if you look at the small feed & Expansion Tank in the loft, is it hot? Is there any visible water movement in it?

 

[chrishutt]

Where is this pipe coming from?

That's the by-pass pipe, running from after the pump and before the 3 port valve. We've already agreed that the by-pass valve should be left shut since there are no TRVs.

 

[bengasman]

the valve indicated by the arrow should be closed. looks like some sort of bypass, no need for that with a 3-port valve

 

[Balenza]

Could the gate valve on the return from the cylinder be seized partially open ?.

 

[Last Triumph]

The bypass is closed.

All gates including exit from cyl (return to boiler) are fully open and opperate smoothly.

I closed the gate that runs to the rads to simulate 'water only' and after about 30 seconds the hum turned to a drone, turned to a louder drone and then a load of gurgling and rumbling occurred and then went away leaving the drone.

I then opened the rads gate valve to resume normal flow and although the pump seemed less strained, it still was much louder than before I opened the rads gate. Over a day or so of normal opperation, it will quieten down again.

All the rads are bled by the way.

The water in the expansion tank is still and cold.

As the kis ave had their bath and the cylinder has now been topped up with cold and the heating is still off, I'm going to measure the hot tap water temp which I guess will be at around the 100F mark.

I'll then switch the boiler/pump on to 'water only' and measure the hot tap water temp every 15 mins to see ho long it takes to get back up to 148F (65C) with all the effort going straight into the cyl coil and withpout the radiators draining heat along the way.

If it takes more that about 30 mins, I know I'ge got a problem I guess?

But why is it so bloody noisy? Grrrr.

Will repor back later.

 

[twgas]

you've already been told the prob...blockage in the cyl coil/return pipe, clear that and the noisewill disappear

 

[chrishutt]

you've already been told the prob...blockage in the cyl coil/return pipe, clear that and the noise will disappear

He's in denial! He's hoping that if he ignores the real problem another easier-to-resolve problem will come along instead.

Speaking of which, what if the cold feed is blocked! Then on the hot water setting the pump might suck air down the vent pipe which would result in a noisy pump. Maybe the whole system is clogged up.

 

[Last Triumph]

Yup, in denial.

Just noticed my other thread has been locked due to breach of forum etiquette. Sorry mods, wasn't trying to be clever, just thought that as the problem diagnosis has moved away from the shower, the title of this thread was no longer appropriate. No offence intended and don't want to come accross as a smart ass.

I'll do some digging tommorrow and report back.

Thanks to everyone who has replied.

 

[Last Triumph]

Right then....

Just before I started splitting pipes, my father came round and offered some help.

Long story short..... after a good session of fiddling with valves, gates, contollers etc (but not actually 'fixing' anything) I have managed to get the 'water only' system working fine - hooray. There was a lot of air in the system and a good few 'fluid hammers', a decent bunch cavitation and bleeding etc, etc and it is much quieter than before, not perfect, but no more noisy than with the rads turned on. So that solves the noisy when on hot watr only problem.

However, our investigations have found another fault. Even with the controller switched to 'water only' water escapes, albiet slowly into the heating system and gently warmes some of the rads.

I removed the electronic part of the valve and opperated it manually and it is still the same. Damn!

I take it that they are meant to seal completely to stop water getting to the rads? If so, I need a new valve.

Anyhow, having got the system now quietly providing me with lots of hot water at 65c nice and quickly, I tried the shower again.

Same problem! Even on full, it'll just about hit 34C which is a luke warm shower at best. I've put the pyro on the pipe just as it goes into the wall and it is 60-62C.

So why on earth won't the thermo mixer valve cut the cold down enough to mix it correctly? I've tried it with and without the pump and it makes no difference. Strangely though, partially closing the flow lever does get it a bit hotter, but this can't be right?

Succes on one hand, but as of tonight, the wife is still grumbling about an electric shower!

 

[chrishutt]

There was a lot of air in the system and a good few 'fluid hammers', a decent bunch cavitation ...

Fluid hammers? Cavitation? What do you mean by these expressions?

 

[barrytheplum]

swap the hot and cold pipes on the shower

 

[Balenza]

Last Tuesday wrote

So why on earth won't the thermo mixer valve cut the cold down enough to mix it correctly?

Duff valve mebbe ?
Id rip it all out and start again.
Your airing cupboard would be the first stop . A sabre saw would remove the lot in about 5 mins flat.
Scrap copper is making a good price these days.

 

[Balenza]

There was a lot of air in the system and a good few 'fluid hammers', a decent bunch cavitation ...

Fluid hammers? Cavitation? What do you mean by these expressions?

He's trying to blind you with the science bit.

 

[Last Triumph]

A fluid hammer is the sudden 'bang' you get when you suddenly release or stop the flow of a liquid or gas. Imagine holding a plug a few inches above the pug hole whilst the water runs away. If you gently lower the pug, eventually the water flow will grab and snatch the plug into the hole with a bang - this is called a fluid hammer. A door banging closed in the wind is another example.

Cavitaion is when the pressure of a fluid drops to to such a degree, normally within a pump or near the blades of an impeller or propeller that gas is released from the liquid. If enough gas is released, large pockets of air can collect and cause all sorts of problems. Some pooly designed ship's propellers used to suffer extreme damage purely through cavitation.

In may case, very quickly and suddenly opening the 3 way valve whilst the pump was on full speed and with the gate vales in various positions created fluid hammers that purged the system of any blockages that may have been there and also trapped air that was contributing to cavitation in the pump.

Hope this isn't why the bypass valve is leaking through to the rads side of the system?

 

[Last Triumph]

swap the hot and cold pipes on the shower

I was very careful to connect the supply the right way round as indicated on the valve. It does get hotter when i turn it to hot and vise versa, just not hot enough.... It's really getting on my nerves now.

As for ripping it all out - I've just spent 6 months and a small fortune totally re-doing the en-suite with new everything - tiles, floor, toilet, the lot. The shower valve is fully concealed and fitted behind all my nice new travertine tiles and aint going anywhere. Jeez, I pray it's not faulty!

I know what you mean about the amount of copper in the airing cupboard. I'd love to meet the plumber that put it all in when the house was built - real artist.

All I've done is taken a hot feed from the pipe leading to the hot taps as per guidlines and instructions, and a cold feed from the storeage tank, into the pump and then off to the shower.