I am stuck. Help needed!
Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

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Ddave
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I am stuck. Help needed!

by Ddave » Fri Nov 23, 2007 7:18 am

I an currently working on a Manchester Open Learning module. I have completed about 13 of these modules on everything from Doors and Windows to Underground Drainage and Insulation, but this one - Central Heating, has me beat! Basically I work for a Builders Merchant and these modules are basic product knowledge stuff. I have done most of this module but now I am
[i]really[/i] stuck. I have about six or seven questions and the final project to do, and I have till Nov 31st. Without help I will not do it, and I hear they charge you for non completion. [b]Can anyone here help?[/b] Many thanks.

marrtin
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by marrtin » Fri Nov 23, 2007 9:00 am

Well post a question, and perhaps someone can point you in the right direction. A lot of experienced plumbing and heating guys contribute to this forum.

Ddave
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by Ddave » Fri Nov 23, 2007 5:24 pm

Thanks Marrtin, OK.
Q.14 Of the consolidation is;
Explain why ferrous and non-ferrous metals are never used together in hot water installations.
Q.15 of the same section;
On a hot water installation only, state the type of cylinder you would recommend and how it would be heated.
There are are 4 more questions and a 'Mini Project' on heat losses, I will post them if I have some luck with these two. ANY help would be greatly appreciated. Thanks again.

marrtin
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by marrtin » Fri Nov 23, 2007 6:15 pm

Metals such as Copper and Iron cannot be coupled directly in a system because of their positioning within the Periodic Table.

The further apart they are, the greater the potential for a chemical reaction with an electrolyte (the water (or the salts in the water)) to produce an electrical current (exactly as a battery works) which would dissolve one of the metals (electrolysis). To combat this, a bridging metal is used that reduces the distance between the elements.

Generally in the plumbing industry, fittings such as radiator valves and bushes which are placed between the copper and steel are made of brass.

Ddave
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by Ddave » Sat Nov 24, 2007 1:51 am

Thanks, thats great. I can at least get that one out of the way. Much appreciated, thanks for your time.

Ddave
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by Ddave » Sat Nov 24, 2007 7:49 am

My reply disappeared!
Thanks Marrtin that helps. At least I can now fill one in! Much appreciated.

Ddave
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by Ddave » Sat Nov 24, 2007 8:11 pm

A couple more...

[b] Q.23 - Explain why Central Heating Systems use 'Zones'[/b]

[b] Q24. - Describe the limitations of the single feed, self priming cylinder (primatic)[/b]

Thanks in advance.

marrtin
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by marrtin » Sun Nov 25, 2007 12:56 am

I posted a reply to your second question, and it never arrived!

For hot water, use a combination cylinder (integral header tank) and immersion heater.

No external links allowed.

Ddave
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by Ddave » Mon Nov 26, 2007 7:03 am

Thanks again - thats brilliant. Getting somewhere now!

Ddave
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by Ddave » Mon Nov 26, 2007 7:07 am

Two more...
Q.21 -
Describe how a mechanical control differs from a thermostatic one.

and

Q.25 - Name three types of heat emitter and explain how radiater tappings are specified.

Thanks. :oops:

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