Hot water Cylinder Type?

Fredser

Hi all,

This is my first post on these forums so hope all goes well!!!

I am trying to discover what type of hot water cylinder is in my house. It appears to be an INDIRECT CYLINDER with the coil being heated from the boiler and then returned to the boiler .... BUT.... yes theres a BUT ..... I only have one cold water tank in my attic i.e. no expansion tank.

Is it possible to have an indirect hot water system like this with only one tank in the attic. The vent from the top of the cylinder does go back to this single water tank but any internet searches Ive done state that I should have a SECOND tank if its and indirect cylinder....

Ive heard of something called a "primatic" cylinder that was used in the past and this kinda matches my setup....

Any plumbers out there???
Help!!!!!!!!!!

Many thanks


Fredser

rooferPete

Hi Fredster,

It is possible to have an indirect cylinder heating off your central heating system without a second (header tank) in the attic.

If your heating is a pressurised system that most gas fired systems are then you are ok, even the oil fired systems work the same way.

Have a look around your boiler and your hot press for a red ball, that said they can be placed almost anywhere on the system but close to the above are the most usual.

Do the pipes entering and leaving the cylinder heat up ? if they do especially the bottom one then you most likely have a presurised system, they are very efficient.

The header tank is mainly used for open systems like back boilers and wood burning stoves.

.

Fredser

Thanks Pete

Sorry for my ignorance but what do you mean by a pressurised system? Does this mean the boiler is fed from the mains?

No sign of a red ball (without opening up the house !!).
What exactly does the red ball do by the way?

By the way the pipes entering and leaving the cylinder get very hot which leads me believe its an indirect cylinder...

Thanks for the answers so far... Sorry for the extra questions!!!

Cheers

Fredser

rooferPete

Hi Fredser,

I have found the pressure vessels under the cylinders in hot presses, floor in the way of course, and in the attic, though not recommened.

The easy way to describe it is the system with a header tank is an open system, the flow pipe can allow the water to expand into the header tank and the water in the tank keeps your system filled with water.

The open system can be used as a gravity system only heating the water and rads upstairs.


The pressure system circulates the same water around using the cirulating pump all the time the boiler is running, they don't have to use an expansion pipe into the attic.

The system can be topped up when needed but most gas systems are left in such a way that only the very handy DIY person or the service engineer can use it.

The advantage with the pressure system is they are usually more effecient and easier to balance the rads etc.

They are very safe unless some genius has interfered with the safety valves, this is very unlikely especially on gas fired heating systems.

Your cylinder should the two pipes for the heating on the same side one above the other and the pipes will only get hot when your boiler is on, some are regulated by a valve on the flow pipe, others have an electronic valve.

The ball (not always round) fills with water but inside there is a bladder that will expand when the water gets hot, there is also a valve on the top for inflating the air behind the bladder when needed.

You will know when this is needed because the furthest radiator will not heat up and venting the system does not improve the heat.

I cannot stress how costly interfering with the pressure can be and should only be carried out by a qualified plumber / heating engineer.

.

Fredser

Hi Pete

Thanks for info. I have no intentions of interfering (wrecking) my system but just wanted some background info before I call the pros in

Where the water is returned from the coil in the cylinder to the boiler there is also a down cold feed from the cold water tank joining this return. Is this normal if the system is pressure fed?

Still no sign of my "red ball" and there is no valve to see either in the hotpress or attic. There is however a standard red stopcock on the pipe returning from the cylinder coil to the boiler. Whats this for anybody?

Any further musings on the subject and the above queries gratefully accepted.

Sincere Thanks

Fredser

beldin

If there is only one tank it usually means a pressurised heating system, is there a pressure gauge on the front of the boiler?? should show 1 bar when cold and go up to 3 bar when on. Some gas boilers incorporate the red ball into their design so that may be why you cannot find it. The stop cock is just to stop the ot water going to the cylinder so that you can reduce the heat going to the cylinder or stop it all together. Do you actually have a problem or do you just want to know what you have????

Fredser

Hi

There is a pressure gauge on the front of the gas boiler showing 0 bar all the time including when heating is on (I assume this is broken!!).

The problem I have is that 2 of my upstairs rads are only heating at the bottom. Ive tried bleeding and Ive also had a go at balancing but no joy...

Any suggestions?

beldin

Okay that gauge should read 1 bar if the system is pressurised. There may be some leak somewhere that has caused the pressure to drop to zero. There should be some sort of connection from the mains water system to the boiler with a stop cock or tap to allow water into the system. Check underneath the boiler and see if you can add in a little water to top up the system. Do this when the system is cold. Then you may have to bleed radiators if there is air in the system and repeat. Do not cause the gauge to go over 1 bar as the pressure will rise when the system is heating to approximately just under 3 bar. There should be a safety valve in place anyway but it is best not to trigger this.

Fredser

Ok i give up...

I found the pressure vessel above the boiler but there also seems to be a pump there???

Would there be a pump on a pressure system?

Also as I said on a previous post there is a cold water feed from the cold tank in the attic joining back onto the return pipe from the cylinder coil back to boiler - Why would a mains pressure system have a cold feed from the cold water tank???

HELLLLLLLLLLLPPPPPP

Fredser

rooferPete

Hi Fredser,

The sytem sounds like a good one, if it depended on pressure only the water would rise and your rads downstairs would never heat, also gas boilers only heat a few litres at a time so you want the water moving through the system fast so it must be pumped.

The system will always need a top up of water, if you ever bleed a radiator where would the replacement water come from ? hence the water supply through the return.

I would have expected a valve on the feed but I'm not a heating engineer, an old trick was to fit two valves on the feed so when the rad had no water to replace the air when being bled the service men looked invincable when all they did was fit a piece of pipe between the valves and top it up.

If it's working don't worry

.

beldin

Okay I am stumped as well. A feed from the cold tank could be used to top up the system but there wouldn't be enough pressure to do that for a pressurised system. Also that would mean water from the heating system could flow back into the cold water tank.

yes a pressurised system would have a pump as all systems need pumps.

Is there any other pipe leading into the boiler
There should be 5 if it is a pressured system
1/ Hot water coming from the boiler to rads
2/ Return
3/ gas
4/ Overflow pipe to outside world
5/ Top up pipe to replenish water in the system

Is the system old or is it a relatively new house

Anyway looks like you may have to contact a plumber for a checkup...

Fredser

Update !!!!!!!!!

The cold water feed from the cold water tank has a stop-cock in the closed position on it. I turned the heating off, opened the stopcock and hey presto this topped-up the system.

The pressure gauage on the boiler had a slight reaction(remember it was stuck at 0 bar) and creeped up slightly to about 0.2 bar (where its since stayed).

Anyway the upshot is, I closed off the top-up cock again and put the heating on ... and it now works - all rads are warming their little valves off!!

Lat remaining mystery:I assume that my pressure gauge is broke though. Unless I should keep the top-up cock open til it reaches 1 bar when cold???

To summarise the system seems to be

* Pressure fed
* Gas Boiler with build in pressure-vessel and pump
* Indirect Cylinder
* Sytem Top-up from cold water tank

The house is only 7 years old! Anybody want to look at this marvelous system feel free to call out to Lucan FOR TEA AND SCONES.

Thanks for all the help.

Fredser

rooferPete

Gawrsh Fredser,

Ye shoulda told me where you lived, the valve is about three feet up the feed pipe just where the shelf cuts your knuckles when turning it

I like Beldin was trying to figure out why there was no valve on the feed pipe, now when your neighbours ask you can tell them

Jackz

Hey Fredser,

There is a little beauty out there called an automatic-filler valve, day one you set your desired pressure by looking at the gauge and then the valve keeps the system at this pressure. The only drawback is if you do develop a leak it will attempt to fill the whole house to 3 bar ! I imagine it reduces call outs for plumbers to people who lack your inginuity! There should also be a blow-off valve on the boiler side of the valve you are using to fill the system. When the pressure gets too high(?) the valve blows a seal off and allows the water to escape (Although maybe this is only neccessary with a filler valve to counteract it screwing up im not sure) !

Anyway all the rads are hot and your sorted!

beldin

These valves are great, bought one for €24 a couple of weeks ago and it saves me crawling in behind the tumble dryer. Plumber quoted by approx 150 to do the same job...

bigtimecharlie

Hi Guy's

I think that you have described my problem. The rad in my en-suite is never hot and I have being bleeding it every week for the last 2 month's. I have now found that a rad in the attic bedroom is also heating to a low level. So with the heating on I am able to bleed the en-suite rad but NOT the attic rad.

So from what ye have mentioned, I should find a valve near the gas boiler where I can open this and allow water to enter the system. I will check this out when I get home from the night shift.

Thank's in advance
Stephen

rooferPete

Hi Stephen,

You should not vent the radiators with the heating on, the pump will only distribute the air around the system.

The valve can be beside the boiler or as in Fredsers case most likely in the hot press, take care when turning on and off valves you are not familiar with, also if there is a valve going into the bottom pipe on the side of the cylinder leave it alone, it could be the setting for the hot water flow into the cylinder.

These valves are usually set by the installer to prevent the cylinder from taking all the heat and leaving the rads where they only get luke warm at best, the opposite effect is to leave you with no hot water and warmer radiators.

Take care when approaching the valves, bring a piece of paper and mark how many turns it takes to open or close the valve, that way you will just use your notes to reset everything.

The valves are usually "Gate Valves" and the can be fitted backwards or upside down, so clockwise doesn't always mean you are opening the valve.

The valve you are looking for is usually 1/2 inch where the others are 3/4 or 1 inch depending on the size of your system.

Take care and have fun.

.

flocker

Some gas system boilers eg Vokera can work at 0.2 bar ( eg from a tank in the roofspace) but should be fitted with a non-return valve.
Better using an auto filling device that only allows 1 - 1.5 bar into the system.
Sometimes the pressure can drop in a sytem and not have a visible leak. This can happen when some types of the platic pipes are used.

bigtimecharlie

Hi Guy's

Found a closed tap on a supply pipe in the hot press and so proceed slowly to open it ( boiler was running at this time). Heard water flowing into system and I carefully monitored the pressure on the boiler and left the system with 1.5 bar with the boiler running. Continued to monitor and later heard water drioping. Checked in the hotpress and found water dripping out of a small hole in the large red tank just above the hot water cylinder.

Turned off the boiler and then opened the relief valve which dropped the pressure in the system to 0 bar. No water dripping now so have called the landlord to investigate.

Have I let too much water into the system? All the rad's were working fine before the dripping was noticed. Is there still air in the ssytem which cannot escape?

Any idea's please.

Thank's in advance
Stephen

rooferPete

OOOOOOOPS ?

I do believe I posted above that you leave the boiler switched off for Surgery ?

The red ball has rubber flap inside like the bladder in real foot ball, it is a set pressure so when the boiler comes on the hot water builds and can't go anywhere except around the system.

Maybe you had it filled with water, the reason you don't run the pump is the system already thinks it's full, it can't tell the difference between air and water unless it has a bottle vent installed.

Try venting the rads which was what you wanted to do anyway that will relieve some pressure off the vessel, when you have the air out you can try starting the boiler.

I think you opened the pressure relief valve which if anything has let more water out than you intended, the boiler should not stay running if the water gets too hot so you should be safe enough.

That type of chance is something an experienced person can take because they are looking at a lot more than one thing at a time.

I think this thread should go into the sticky box as a lesson that there are some things that can't be fully explained in a post.

I would go further and include anything to do with DIY Gas or Electrics should not be encouraged.

flocker

Stephen,

it could be that the pressure vessel is faulty or the internal bladder is bust. It doesn't sound good when their is water dripping from it when the system is pressurized.
One thing to check, there should be a valve (similar to a car tyre or bike) on the vessel try pushing the centre pin down and see if you hear air escaping. If there is air coming out the pressure vessel could be OK and the leak is coming from a bad joint. If there is no air the pressure vessel could be flooded and will need to be replaced.

As you said

so have called the landlord to investigate.

leave it to him to sort it out.

rooferPete

Hi Stephen,

I think Flocker missed the part where the only problem you had was a rad not heating properly.

My suggestion is if the landlord is sending a plumber over let him do his job, if he is an ok tradesman he will fix the problem and not mention you interfered with the system.

Flocker is right it is unusual to have water coming out of the vessel but there could be a pressure relief valve that allowed the excess water out.

The plumber will not thank you if he finds the air pressure is gone out of or dropped below the normal in the vessel because he will have to pump it up again.

All the parts in these systems are designed to stop the boiler working if there is a problem, so I would agree with Flocker.

leave it to him to sort it out.

.

bigtimecharlie

Problem solved:

Landlord ( who is a builder) inspected the system and seen that there was no pressure in the system and so opened the valve ( which I had opened previously) in the hotpress. Now some water leaked throught the hole in the red ball unit. Closed the valve and the leak stopped. He suspected that the red ball had corroded friom the inside and hence was not able to take the pressure. So he replaced the ball over the weekend and when I checked on my return, the pressure reading above the boiler was 1 bar and when the heating kicked in it increased to 2 bar.

bigtimecharlie

So now with the heating back to full working order, I checked the rad's while the heating system was on. The rad in the en-suite was cold with only heat at the very bottom. So I opened the valve in the hotpress for a few second's and checked the rad a few minutes later. The rad was hot to about 3/4 up.

Should I continue to let water into the system gradually ( boiler off) as the rad in the attic is cold also? Also the pressure in the system seem's to have fallen over the last week.

flocker

Bigtime,
you will probably need to bleed the rads, probably best to check all of them. Then check the pressure and top up if necessary.