Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder??

[robdav]

I have a fortic cylinder in the loft heated by an oil fired boiler. I have traced all the pipework and understand all but one of the pipes. This pipe is related to a problem I’m having with the shower getting slowly colder and colder after a minute or so of use but there is plenty of hot water remaining for the tap in the kitchen and bathroom.

The fortic cylinder was installed about 10 years ago and came from Plumbase but has no make or model details on it. It's a relatively straight forward setup as far as the tap in the kitchen and bathroom are concerned. Using hot water from these taps causes the ballcock to drop and the cold water supply to start filling the cold tank as the cold water drains down into the hot water tank below. On one side of the tank there is a very obvious cold feed coming in to the header tank and hot water pipe coming out of the top of the hot water section feeding the taps.

However, on the other side of the tank there is another pipe coming out of the top of the hot water section feeding the hot water pipe to the shower, which is almost directly beneath, so far so good. There is also another cold water feed pipe from the mains which goes to the shower, and this is the interesting thing, it also feeds into the hot water tank about 3 quarters of the way up. This doesn't make sense to me.

I tested turning off the isolation valve on this cold water feed expecting this to only leave hot water coming out of the shower but it left no water coming out of the shower, neither hot nor cold. The shower is a 20 year old bar shower made by a company that doesn't seem to exist anymore (Showermax TMC153 by IMI Range Limited). Could this be the thermostatic valve in the shower turning off the water in this test?

I don't mind replacing the shower as I understand the thermostat inside it may well have gone/furred up. However, it doesn't explain the almost secondary cold water feed directly into the hot water cylinder unless the hot water cylinder could have two sections inside it? Is this possible?

I have attached two photos which I hope will help but they aren't great as it's cramped and dark.

This picture shows the fortic tank, with the hot water pipe coming out and feeding the kitchen and bathroom tap. You can also just see the cold water feed going up on the right to fill the cold water header tank.


This picture shows the other side of the same tank (opposite side to picture above) with the hot water pipe running (over the big grey bathroom steam vent pipe) down to the shower below. It also shows the cold feed running on the floor feeding both the cold feed for the shower but also going into the tank.



Any ideas would be much appreciated.

Cheers

Rob

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

It sounds like you have an IMI Showermax cylinder.

The cylinder acts as a thermal store - the incoming cold water main is passed through the heated main section of the cylinder, gains heat, and is delivered as hot water to your shower. In all other respects, its an ordinary fortic.

Whats the problem with it?

 

[robdav]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

The problem is the shower temperature starts dropping after 3 or 4 mins and yet there is still plenty of hot water coming out of the bathroom/kitchen taps immediately after getting out of the shower.

Where would the IMI Showermax cylinder be and how big would it be? Or are you saying there is an additional heating coil inside the hot water cylinder just for the shower or is the water in this cylinder heated as a result of the second hot water tank inside the cylinder? Are you aware of any diagrams/instruction manuals on the web that can help me visualise this?

Is there anything that can be done to get a longer hot shower out of it so two people can shower?

Thanks Ray.

 

[tamz]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Can you still get showermax cylinders Ray??

To the op
Your cylinder has a heat exchanger inside just for the shower. Cold water goes in one side, runs through a high output coil and picks up heat from your tank of water then comes out and goes to the shower. If you turn the hot supply (or the cold) off, the shower valve is designed so that it cuts both supplies (it is a safety feature).
You still have hot water to your taps (it will be cooler but still hot) when the shower starts running cold because there is no longer enough heat transfer from the tank to heat the shower supply ie the water is running through the heat exchanger faster than it can pick up enough heat.
It could be down to scale build up on the hw coil. Try throttling down the supply to the shower (close the valve a bit) which should give you a bit longer shower. Also check your thermostat setting on your heating system and turn it higher if necessary.

 

[tamz]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

The IMI cylinder is the big blue tank in your picture.

 

[robdav]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

I understand now so thank you tamz.

Regarding the thermostat, is this the thermostat on the hot water cylinder or on the boiler itself? I also read this "The control knob on the front of your boiler sets the temperature of the water it produces, and this is the temperature your radiators will be when your heating is 'on'. This control also needs to be set so the boiler delivers water at a higher temperature than set on the cylinder thermostat, or the cylinder will never reach the selected temperature and the cylinder thermostat will never shut the boiler down"

Thanks, Rob

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Can you still get showermax cylinders Ray??

I don't think so - I haven't seen a new one for years.

Obviously it would be possible to get a fortic made with a secondary coil, but i am not sure of the showermax coil spec. It must have been quite a long coil, with a hell of a surface area.

 

[tamz]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

I only ever fitted one Ray. Quite a rare beast up this way.

Rob this is a picture of something totally different but the inside of the cylinder looks something like this. Your shower connections are like the top right connections. You have (should have) a thermostat on the side of the cylinder. Check what that is set to. Also check the thermostat on the boiler. If it is set too low the cylinder can only heat to that level.

 

[robdav]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Thanks, that helps to visualise it.

So if dropping the pressure and upping the temperature only goes so far, it's probably down to calc build up on the elements making them less efficient and the only option is a new hot water cylinder?

 

[tamz]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

You can't get in to descale the coils so it may mean a new tank.

An easy way to restrict your shower is to buy a half inch tap washer, unscrew the shower head from the hose and pop the washer in. You will still get a good shower but with half the flow rate.

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

I only ever fitted one Ray. Quite a rare beast up this way.

They were specced on a few newbuild sites down here in the 90s, but it was rare as hen's teeth in one-off jobs.

There was another unit, can't recall the name, which used a jacketted co-ax internal coil, and a little pump to keep the thermal store water moving across the surface of the inner, heat exchanging coil. One of the potential issues was that the thermal store water around the shower coil would drop in temperature, and although the store as a whole had plenty of heat, a cooler pocket would develop, and shower temp therefore drop.

I'm wondering if that is happening here, perhaps with the added issue of a bit of scale build up, and the very low incoming water main temp?

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

I've just emailed RM to see if they make a replacement. Richard Marsden (the RM in RM Cylinders) owned IMI Range for a while before flogging it to Kingspan, so he and his techies are likely to have a good idea of the spec.

 

[tamz]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

They were specced on a few newbuild sites down here in the 90s, but it was rare as hen's teeth in one-off jobs.

I got that one from UBM's when the branch was closing (after PTS took them over) along with a whole load of other stuff they were getting rid of so that was sometime in the late 90's. It was probably left over from some site order.

 

[robdav]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Many thanks Ray, would obviously like to hear from you if you get a response back from Richard Marsden.

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Many thanks Ray, would obviously like to hear from you if you get a response back from Richard Marsden.

No worries RobDav, I will let you know. It's not likely to be until Monday though, cos I am off work tomorrow (Mrs S's birthday)

 

[Mike Jackson]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Can't see anything in the IMI catalogue but you could upgrade to an Electric 7 flowmax and put all of the hot at mains pressure. Have a look at http://www.range-cylinders.co.uk/pdfs/sales/copper.pdf page 27

 

[Ray Stafford]

Re: Fortic cylinder/shower hot water oddity. Dual hot water tanks in fortic cylinder?

Many thanks Ray, would obviously like to hear from you if you get a response back from Richard Marsden.

Just spoke to a techie at RM who remembered the Showermax from when they owned Range.

They do a replacement unit called Showerheat, but there are a couple of issues. Firstly, its hideously expensive - I don't give prices on the open forum, but trust me, you don't want to buy one. It would be a four-figure price.

Secondly, he explained some of the problems - for the shower to work properly, the cylinder needs to run at 75 deg with the other issues that this brings, not least the excessive build up of scale.

Their strong recommendation was to replace with an unvented cylinder.