Thursdays Job - Change Hot Water Tank

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Gulp!!!
Okay, I am adequate with basic plumbing, using compression fittings, and just learning solder fittings now.
My old Elson hot water tank is leaking, and I have bought a Fortic F3 indirect water tank. So Thursday is D-Day. Can I pick your brains. I just want to confirm the questions I have just now - I believe I am right but don't want to have a tank full of water and realise I've fecked up!!
I assume that the bit in the middle is the feed from the central heating, to keep the water warm. I have to drain either the lowest radiator or the external drain cock to empty this?
http://mmillar0.tripod.com/tank/old_tank_2.jpg
Are these markings correct?
http://mmillar0.tripod.com/tank/old_tank_pipes.jpg
I notice the reducer - what size would these connections be? I am a metric guy - this tank is about 30 years old!
http://mmillar0.tripod.com/tank/size_central_heating.jpg
http://mmillar0.tripod.com/tank/size_hot_water_pipe.jpg
On the new tank - I assume this is for an immersion heater
http://mmillar0.tripod.com/tank/big_hole.jpg
These go into a coil, so for the central heating connections?
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SantaUK
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Gulp!!!
Okay, I am adequate with basic plumbing, using compression fittings, and just learning solder fittings now.
My old Elson hot water tank is leaking, and I have bought a Fortic F3 indirect water tank. So Thursday is D-Day. Can I pick your brains. I just want to confirm the questions I have just now - I believe I am right but don't want to have a tank full of water and realise I've fecked up!!
I assume that the bit in the middle is the feed from the central heating, to keep the water warm. I have to drain either the lowest radiator or the external drain cock to empty this?
http://mmillar0.tripod.com/tank/old_tank_2.jpg
Are these markings correct?
http://mmillar0.tripod.com/tank/old_tank_pipes.jpg
I notice the reducer - what size would these connections be? I am a metric guy - this tank is about 30 years old!
http://mmillar0.tripod.com/tank/size_central_heating.jpg
http://mmillar0.tripod.com/tank/size_hot_water_pipe.jpg
On the new tank
http://mmillar0.tripod.com/tank/fortic_f3_tank.jpg
I assume this is for an immersion heater
http://mmillar0.tripod.com/tank/big_hole.jpg
These go into a coil, so for the central heating connections?
http://mmillar0.tripod.com/tank/ch_heating_connections.jpg
Correct with this one too?
http://mmillar0.tripod.com/tank/connections.jpg
I assume the drain cock etc is a standard size?
http://mmillar0.tripod.com/tank/drain_cock_size.jpg
http://mmillar0.tripod.com/tank/hot_water_size.jpg
http://mmillar0.tripod.com/tank/immersion_heater_size.jpg
On the one I believe is for the immersion heater, I trust I can buy a stopper for it, and just block it off.
On my old tank there is a thermostat control, this is secured from the inside of the tank - how would I fit a new one?
I know these questions might seem basic to you guys - but please bare with me - intruder alarms and CCTV are my thing!!!
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SantaUK
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"SantaUK" <Aye Right!!!> wrote in message

Those original fittings look imperial 3/4" to me so I would stock up with come converter parts. You can get a special olive that fits into 22mm compression fittings to close down on 3/4" pipe (in fact I have some in my toolbox!) If you get a 22mm coupler, and fit the special olive in one end, you can run from the existing 3/4" piping via the fitting onto new 22mm pipe to your new tank. Just remember that you always need more bits than you thought !
Andrew Mawson
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olives even though packed as converter olives.
Experience.
Rod
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Noted!
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SantaUK
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Thanks for that

When I drained the tank, (having now thought I should have photographed it!) inside is a drum at the bottom, and the other small tank you see in the photo. The water level in this didn't budge at all, which is why I believe it is the Central Heating.

Only thing Shed's are good for :-))

Having checked the web for a blank plate and having no luck, I think that would be the easiest solution!

Bud I did find this in the hunt for the blank - cheers.

Again - excuse the ignorance, but the tank has a feeder at the top - I have no cold water storage in the house at all. Isn't this the job role of the feeder on top?
Thanks for your time
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M Millar
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On Sun, 14 Dec 2003 17:54:38 -0000, "SantaUK" <Aye Right!!!> wrote:

True, but remember that you are lending them money, even if you take the goods back.

The small tank on the top is a cold water feet to the hot cylinder below on the Fortic tank. It doesn't supply the boiler primary at all. If you look at the diagram, the coil inside the new tank is totally isolated from the rest of it.
You must have a small header tank to handle filling, expansion and venting for the boiler primary circuit. Don't just connect the pipes to the coil of the new tank because there will then be no provision for expansion of the water. This is very dangerous and something will give, probably explosively.
That's why I suggested contacting Elsy and Gibbons with the model number of the old tank. It seems likely that it does have provision for filling and venting the primary circuit but it's impossible to tell that from the photos. You really do need a positive confirmation of what you actually have. It's possible that there is an arrangement whereby the principle of the now deprecated Primatic tank has been used. This was a system using a vessel and air bubble arrangement in the HW cylinder where the primary circuit was filled from the secondary water. It kind of separated the two but not properly and you couldn't add inhibitor. If this tank has that arrangement, then it is OK to replace it with the fully indirect one that you have, but you MUST make the arrangements for the filling, expansion and venting of the primary.
This will involve using a small 4 gallon plastic tank and fitting it at a level above the highest point of the primary circuit. The specification of the boiler will tell you by how much, but normally at least 0.5m. I assume that since this new tank is in the loft, that the top connection of the cylinder will be the highest point of the primary system. If that is the case, then the small header tank will need to be fitted at a level above that - probably about level with the top of the Fortic tank.
This header tank will need a connection near its bottom and a pipe run in 15mm to the primary circuit. There should then be a 22mm pipe run from the highest point of the primary circuit and looped over the top of the header tank. You will then need a ball valve on the tank of a type suitable for the temperature with a supply from the mains in 15mm run to that. Obviously the header tank will need to be supported properly and lagged. The header tank will also be the place where you can add chemicals such as inhibitor when you have cleaned and flushed the system.
Do please do your homework on this and make sure that you understand what you are doing and what is connected to where. If you are not 110% clear then don't attempt the job. There is a definite safety issue here.

.andy
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And this is the exact reason I posted to the newsgroup first!!! Thanks for your feedback. I did overlook the coil part - I assumed (assumption - the mother of all cock ups!) the boiler would fill it, but I didn't think of expansion.
I have drawn a diagram and emailed it to you. Is this what you are talking about? Its also at
http://mmillar0.tripod.com/tank/diagram.jpg
From drawing that - I have assumed that a simple T piece at both junctions of the (CH IN and CH Filler) and also (CH IN and the Expansion) pipes.
From what you said about adding the inhibitor etc - I know I can't do that with the currect tank due to the design of it. A plumber I know (who stays about 500 miles away or he would be doing this for me!) did mention that I would need another header tank - but didn't go into detail as whey - and to be honest I didn't pay attention to that as I knew best ;-))
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SantaUK
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On Sun, 14 Dec 2003 20:52:41 -0000, "SantaUK" <Aye Right!!!> wrote:

In a sealed system you would typically have a filling loop (a small braided hose and valves) near the boiler. The expansion is taken care of by a pressure vessel which may be in the boiler or outside or in a larger system, both.
You didn't say what boiler you have, but from the existing tank it was clear that it wasn't a sealed system. If the boiler is recent, it may be suitable for sealed system operation, in which case you could add a sealed system kit instead of the small header tank. Again, don't consider this without going into the details of the boiler. If it's of an age approaching the tank then it won't be suitable.

I've got the mail. Unfortunately the web site has become unavailable because the bandwidth has been exceeded.
However, this is pretty much it.
- The feed pipe and the vent pipe should connect to the circuit no further than 150mm apart to avoid sucking down of air or pump over from the vent.
- Another way to hook up is to use an air separator like a Myson Aerjec.
http://www.bes.ltd.uk/products/106.asp code 11334
I had one on my system before it was converted to sealed operation and they work very well as well as being a convenient way to hook up.
- Opinions differ as to which way round to connect the coil. Some people say flow at the top as you have it. Others say the opposite.
- You remembered an overflow for the header tank. Good - I forgot that.
- The feed pipe from the header tank should be at about 50mm up from the bottom.

Or the air separator idea. Heating and plumbing merchants have them and I did see one in B&Q once.

There you go :-)
.andy
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Cheers - seen the problem with the website:
http://homepages.nildram.co.uk/~mmillar/Diagram.jpg
http://homepages.nildram.co.uk/~mmillar/2nddiagram.jpg ( Found this one on a web page tonight - looks neater than mine!! )
Its a fairly new Potterton system - installed three years ago. Don't fancy messing around to see if I can make a sealed system, think I'll be able to go ahead on Thursday with your information.
So just to reiterate literally a T piece on the CH In line up to the CH header tank will suffice for expansion?
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SantaUK
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On Sun, 14 Dec 2003 21:33:05 -0000, "SantaUK" <Aye Right!!!> wrote:

This one is a bit questionable because it has the feed pipe connecting at some distance from the vent pipe and possibly the other side of the pump. You definitely don't want that.

Plus the vent from a point close to it.
.andy
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So stick with my drawing and all will go well!
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SantaUK
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On Sun, 14 Dec 2003 21:45:44 -0000, "SantaUK" <Aye Right!!!> wrote:

With the feed pipe near the bottom..... .andy
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I see what you mean - will do!!!
Of all the times I decide to get my finger out my arse and do it, I pick the week before Xmas.
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SantaUK
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SantaUK" <Aye Right!!!> wrote in message

Pardon me for butting in, but one thing's bothering me - the pipe sizes. The primary flow and return to the old tank are " copper by the look of it. Will it be OK to connect these to the new cylinder - will this give enough heat for the 22mm dia coil, and is it OK to have a 15mm vent to the new F/E tank? I've always thought vent pipes should be 22mm but I could be wrong of course!
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They certainly are - Andy - you're turn!!!
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SantaUK
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On Sun, 14 Dec 2003 23:43:47 -0000, "Peter Taylor"

I can't get the pictures back now, but I don't remember the pipes being small - you might be right though.

It would make recovery fairly slow especially if the tank is in the loft and the boiler is on the ground floor and it's 15mm all the way. If so, it ought to be upgraded.

The vent should be 22mm or more as I mentioned earlier. The feed/expansion pipe at the bottom of the header tank can be 15mm.
.andy
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Def 15mm pipes, but don't know if all the way - will check tomorrow. But failing that - I will go ahead with the change anyway - just ordering the parts from Screwfix just now. If it is too slow, then I'll probably use the immersion heater that we mentioned earlier as a booster.
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SantaUK
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On Mon, 15 Dec 2003 00:51:10 -0000, "SantaUK" <Aye Right!!!> wrote:

That would get expensive and with a 3kW immersion heater, the norm, not very effective.
If you have 15mm pipes most of the way, you would get around 4-6kW to the tank from the boiler anyway.
If you can't do the whole job at once, then I would suggest cutting back the 15mm as far as you can go easily for now and running in 22mm and then upgrade the rest when it is more convenient.
The thing for the moment, I suspect is to get something going as quickly as possible, so don't take on more than you can do in the time available. Just organising the CH stuff and putting in the new tank will take a fair time if you are not a regular plumbing practitioner.
.andy
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Not sure if you're getting my drift Andy. It's not safe or wise to tee the new 22mm vent pipe off a " pipe, which is what's shown on Santa's sketch. The vent needs to be teed off a 22mm pipe nearer the boiler, probably at first floor level. This means the feed has to be taken lower down nearer the boiler too.
All this involves no less work than completely replacing the " F&R pipes to the cylinder with 22mm, with the tees for the 15mm feed and 22mm vent near the cylinder as per the sketch. This would be safer and wiser, there would be 2 less rising pipes at first floor level and it would also minimise the recovery time. And if there isn't one already, wouldn't it be a good idea to grab the chance to install a cylinder stat and MV to control the HW primary?
As a very temporary measure before Christmas, the new 22mm F&R could be taken just below the first floor ceiling and connected to the old " pipes and the remainder replaced later, but this means draining down twice.
Hope all this makes sense! Peter
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