Re: OT: Intro + Q:Selecting workshop heater

At 08:33 22/12/00 +0000, you wrote:

>Not really a 'bundle' of pipes - Microbore is a system which is popular in
>parts of Europe but, for some reason, hasn't caught on with the majority of
>'traditional' plumbers around here. I've put 5 systems in with it so far
>without any problems - all working fine and I'm not a professional plumber.
>The way it works is that the boiler feeds into a header pipe of about 1"
>copper which takes the primary distribution to the centre of the building (2
>separate fedds for 2 floors etc.). Here it terminates in a 'manifold' -
>often called a 'sow' as it is a straight piece of stronger pipe with small
>compression couplers along each side and a capped off end. A similar pipe is
>laid in for the return so that you have, at a fairly central point, two
>manifolds with a number of connections. From these, small diameter - 6, 8 or
>10 mm - flexible plastic pipes are taken to each radiator - a separate flow
>and return pipe from each radiator to the repective manifolds - thus the
>flow in the 1" pipes is now equally divided between a number of smaller
>pipes.

Also uses copper pipe in some installations (such as in my own house). The
copper pipe is bendable without the use of "pipe benders" as long as you
don't use very tight bends.

>The advantages of this method over a more 'traditional' system are:-
>1. The pipes are easier to run - you can work them just like electrical
>cable, thread them through small holes in timberwork, fix them with ordinary
>one nail wire clips etc.
>2. Every radiator gets the same full heat - you don't finish up with a
>radiator at the end of the system which is cooler than the rest.

In practice, the flow through each circuit will be affected by the length
of pipe run in each flow/return - twice the length of pipe will give twice
the resistance to flow; similarly, if you mix the 6, 8 and 10mm diameters
in the same installation - this is straight "Ohms Law" stuff. But it is
easier to balance flows than with a small bore or large bore installation.

>3. Adding another radiator is easy - you make sure at first installation
>that the manifolds you fit have spare ways on them which you cap with
>blanking plugs, then, when you want to fit another radiator, you simply
>mount it on the wall, run another pair of pipes to the nearest manifold, and
>hook it in.
>4. Unlike a 'traditional' system, you don't have to worry about slopes on
>pipe runs and airlocking. When you use a system with 1/2" pipe, this has to
>rise steadily from the feed to the return or you will get airlocking and
>cold radiators. With microbore, the pipes are small enough for any air
>bubbles to get carried along with the flow and so you don't get airlocks. In
>fact, you can run pipes upstairs, downstairs, wherever you like with no
>problems.

Hmmm. Nice theory, but I can show you an installation here in my house
(NOT installed by me) that can and does create horrendous airlocks if you
don't re-fill the system carefully after draining it down. Had a plumber
in to do some mods on one occasion - it took him the whole of a morning to
bleed out all the airlocks.

>5. Because the plastic pipe comes in 50' coils, you don't have any joints in
>the pipe runs to leak.
>
>In your case, if you are just wanting background heat, why not try just
>running a big loop of plastic pipe around your workshop? This could just be
>an extension of the feed to the hot tub - what I mean is break into the feed
>from the boiler to the tub - send it through a long loop (or loops) of pvc
>pipe around the workshop, and then recouple it into the tub end. I don't
>know how the temperature control on the tub works, you would lose a few
>degrees on the feed water temperature this way, but if the thermostat is on
>the tub and the boiler is up to producing enough heat for both the tub and
>the workshop, you shouldn't notice any difference. Perhaps you could
>increase the flow rate to compensate. At least this way you wouldn't have to
>worry about using copper radiators etc., and, if it didn't work, you could
>put things back to normal easily.

You haven't mentioned the one major disadvantage - if you live in a "hard
water" area, the pipes fur up really quickly unless you take steps to
soften the water.

Regards,
Tony