I've just done most of the pipework up to the new combi. There is just the connections to the unit to complete. Do I just use elbows to make that tight turn to meet the combi connections?
Also, I haven't done the gas supply pipework yet so this pipe would have to leapfrog a horizontal section of the mains supply to the unit. Is this acceptable?
Thanks.
Arthur
In article , Arthur writes
System connections (the big stuff), swept bends essential. Feed & h/w connections swept bends recommended. ie. not elbows.
Prob not what you wanted to hear . . .
Thanks.
The pipework I've done so far is still shy of the combi by a foot or so. What are these system connections you mention? Do you have a link?
Arthur
The system connections are the ones to and from your central heating loop, probably 22mm, possibly 28mm. 22mm is right on the limit for passing enough water to distribute the heat from the typical domestic boiler so it is not a good idea to restrict the flow with the use of elbows before the distribution tree starts to split off to different parts of the house. Better to create bends from straight pipe using a pipe bender giving a smooth radius to the bend of about 80mm.
Cold feed and hot output can be 15mm as hot water generating capabilities of combis are limited but again swept bends mean less restriction and less noise.
Regarding your last question on the gas supply, you shouldn't really need to create a tightly bent rats nest of pipework, subtle return bends in your CH/HW & gas pipework should allow pipes to pass in opposite directions without this happening. Try not to fit one set of pipes then force others to fit around them, design the layout of the pipes on paper before hand, it worked for me.
For more info, have a look at the heating section our very own faq:
- Change the stop c*ck to a "full bore" stop-c*ck.
- Make sure the combi has a dedicated, preferably 22mm, cold water inlet pipe right back to the main stop c*ck, even if the mains is only 15mm.
- Do not tee cold supplies off this pipe.
- Take the hot supply of the shower right back to the combi outlet.
- The cold to the shower: have teed off the cold water inlet to the combi, just before the combi. This should be the "only" cold water pipe teed off this pipe. This is so when there is pressure fluctuations around the combi the hot and cold to the shower are influenced at about the same rate.
- The shower is the most important outlet in a water system, All must be geared to ensure constant pressure and volume to the mixers.
- use bends where possible and elbows when there is no alternative.
If you have not done this I strongly advise you to do it while you at this stage.
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If you are going to change your stop c*ck, make sure you fit one that conforms to regulations, as fitting a non approved one could lead to prosecution by the water authorities. IIRC a stop c*ck BS1010 with a loose jumper must be fitted as it acts as a non return to prevent any contamination getting back into the main.
Loose jumper? Not so. Many water companies are now installing full bore valves lever valves. Many charge around £70-80 to fit one.
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If they fit a full bore valve (which still has to meet the required BS) they are also required to fit a double check valve to prevent backflow, which rather defeats the object.
The only advantage is that you are able to shut off the incoming supply easier when they aren't seized.
The disadvantage we find with full bore lever valves is that they need exercising more often, as they are prone to seizing in hard water areas. In fact I've got to replace a 50mm Boss full bore in an industrial unit next week for that very reason.
A 15mm stock-c*ck can seriously reduce pressure and flow. You can always fit a larger sized double check valve to improve flow combined with full bore valve.
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True, but is it worth the effort?
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