Secondary circulation Book .

[verdigrey]

Hi , can anyone help please . I need to design & price for installation of the Cold mains & D/H/W for a proposed new house . The customer wants secondary circulation on the Hot side . Because of the high demand for hot water I am going to suggest an unvented cylinder heated by an oil boiler . Does anyone know of a book that covers this in detail please .

 

[bobpape]

Hi Verdigrey
Where is the correlation between a "high demand for hot water" and an "unvented
cylinder"

 

[Hugh]

dude you got to have your ticket for un-vented cylinders!

 

[verdigrey]

Sorry bobpape , When I said high demand I meant high demand for pressureised Hot water . In this house there will be 3 shower rooms requiring powerfull showers , 1 bathroom , kitchen & utility rooms .
Yes I know I will need my Unvented ticket Hugh, but as the work wont start for about three months I am hopeing to get it before then .
Any thoughts about books please .

 

[bobpape]

Even if you put an unvented cylinder on each of the three showers you would not be able to use all three at the same time or even two at the same time, a combination boiler or boilers would not be any better.
I am afraid you will have to install a conventional system,perhaps with a pump,

 

[Plouasne]

Even if you put an unvented cylinder on each of the three showers you would not be able to use all three at the same time or even two at the same time, a combination boiler or boilers would not be any better.
I am afraid you will have to install a conventional system,perhaps with a pump,

Doesn't this all boil down to basic design of the system

If the incoming main can supply both the pressure, and the volume required, I would go for an all mains pressure system

 

[bobpape]

Hi Plouasne
Where in the UK or indeed any where in the world would you expect to find a water main
supply of sufficient pressure to supply three showers satisfactorily at the same time,

To satisfy that kind of demand one would have to first store some water either in an under tank and pump it or in a high level cistern.

Dare I say it Plouasne judging by your mini autobiography in earlier posts (which in
some respects parallels my own except I first went to SA in 1956) You know full well
that in terms of good plumbing Multipoints, Combi Boilers, and now Unvented Cylinders, are of little use in a three (or even a two) bathroom house.

Me thinks you are just up for a row because like me you are retired and have nothing better to do

 

[Plouasne]

Hi Plouasne
Where in the UK or indeed any where in the world would you expect to find a water main
supply of sufficient pressure to supply three showers satisfactorily at the same time,

To satisfy that kind of demand one would have to first store some water either in an under tank and pump it or in a high level cistern.

Dare I say it Plouasne judging by your mini autobiography in earlier posts (which in
some respects parallels my own except I first went to SA in 1956) You know full well
that in terms of good plumbing Multipoints, Combi Boilers, and now Unvented Cylinders, are of little use in a three (or even a two) bathroom house.

Me thinks you are just up for a row because like me you are retired and have nothing better to do

Try the 72" main that runs or did run from the old MWB water works near Kempton Park to new River Head reservoirs London

Or the Liskeard water works to Looe 12" main, I came straight off that with 14 bar pressure behind it, say 200psi or about 400 foot head, worked a treat that did

How do you think that large blocks of flats, hospitals, with a central hot water supply, work if not off a calorifier, boosted pressure or not, if you care to read my posting I did qualify my statement of, "If the incoming main can supply both the pressure, and the volume required" by saying that it all boils down to design, in the first place

A very rough top of my head guesstimate, I would hazard a guess that a 54mm cold water incoming main with a 3 bar pressure would be sufficient for the job concerned, together with a 500litre or better a 1000litre calorifier, suitable for 3 bar pressure as the hot water storage; I do not know the UK regs for this but in France this would be a normal plumbers job, because this would be considered a slightly larger than normal hot water cylinder, and these are tested to 10 bar, with a normal working pressure of 3 bar

But as I first posted the system does require proper designing, not guess work or rule of thumb, for it to be satisfactory to both the client and the installer

 

[Bernie2]

My guess is that he is trying to do it all off a 25mm MDPE main and about 1 or 2 bar max.

He must work to the lowest common denominator anyway and that is 1 bar at 9 liters flow that is all your guaranteed after that its up to the house owner. Unless of course its a bigger than normal premises.

The multi stories in my area seem to be supplied either off break cisterns and pump sets with zone break cisterns, or automatic pneumatic cylinders.

The heating and hot water can be drop fed from roof boilers, with individual controls at each flat or individual boilers and circulaters flueing into SE ducts.

 

[Jimbob]

there is nothing to the design of secondary cirulation... as for a book. Do u mean to help with the sizing of cylinder or the design of a secondary return? for a place that size id go for at least a 170 litre unvented cylinder, if not larger. Look on the heatrae sadia site at megaflo's, there one of the better cylinders IMO.

 

[Plouasne]

I would say that 170 litres capacity is way too small, all the recommendations for something like what the OP wants, is a minimum of 300 litres if not 500 litres

In my opinion you could be hard pushed to beat these two the descriptions are in English as well

[DLMURL]http://www.atlantic-comfort.com/documents/installation_manual_Combi_MG.pdf[/DLMURL]

http://www.pacific.tm.fr/pdf/notice_PECS.pdf

 

[verdigrey]

Sorry for the delay in posting , Thanks everyone for your advice , Yes Plouasne it is down to the basic design of the system .
I have recently been told by the guy that owns the building plot that the mains pressure is sometimes not very good ( it is in the country near the end of the main )
Yes bobpape the safest thing is to have a conventional system ( not unvented ) and use a pump . Also have plenty of storage for the cold water in the loft .
Thanks , Verdigrey