DHW manifold arrangement - options?

[TonyT]

Joint at the manifold so any potential leak is above floor level

 

 

[Jenki]

On 02/05/2023 at 15:49, Super_Paulie said:

In regards to the fish, hell yeah! the novelty wore off very quickly using buckets etc so i have a hot and cold feed that i mix with valves. Might get a TMV as an upgrade as the temperature always needs to be the same really. They double up as a syphon as well to drain the old tank water away via a pipe to a soak away outside and its an absolute lifesaver, can recommend.

@Super_Paulie I used a TMV, and although the spec doesn't say you can get below 30 deg, I managed to get 26deg accurately. it was a god send.  if I was planning again, I would also plumb in a suitable waste for the water changes. (I used a pump and hose for a 500L tank)

 

ADDED INFO.  If you add a TMV you can put this next to the manifold and run only 1 feed?

 

Edited May 10, 2023 by Jenki
Spelling / more info

[Jenki]

1 hour ago, TonyT said:

Joint at the manifold so any potential leak is above floor level

 

 

+1  minimise all joints that's the whole purpose of the manifold.

[Nickfromwales]

On 02/05/2023 at 15:49, Super_Paulie said:

They double up as a syphon as well to drain the old tank water away via a pipe to a soak away outside and it’s an absolute lifesaver, can recommend.

Just an aside, but you’ll need to fit double check non return valves onto the hot and cold feeds to the fish tank if you’re back-flowing dirty tank water through pipes; which are connected to the potable water system. There’s a high risk of back-contamination of your drinking aka potable water system from doing this. 
The NRV’s need to be 1x hot and 1x cold, on each of the individual supply lines to the tank. Or, combine the feeds at the manifold into a TMV, and fit a s1x DOUBLE check valve on the output of the TMV. 

[Super_Paulie]

ideally id put the TMV at the aquarium end so i can easily manipulate it but its a good shout. I did plan on doing that originally as i made the 2 feeds with the 2 NRVs but in the end i just stuck an elbow on in with some pipe to mix it. Not sure why, think i lost interest in the job but i already had the 2 NRVs in place ready which seems mental to sack it off right at the end. When i re-jig this i'll use the TMV and rebuild to just have the one NRV and lose all the copper as its meant to be bad for the fish and shrimps but ive had no problems there since i put it in. What i do is use a speedfit connection and then have a removal cleaning "wand" that is basically some hose clipped to a small length of 15mm pipe with an end on to stop the fish ploughing down the hose and into the soakaway, then i just remove it from the speedfit fitting when ive cleaned it. The syphon works class and its incredibly easy to drain and fill the thing up, which is a horrendous job when the tank is in the front room.

 

 

[Super_Paulie]

On 10/05/2023 at 07:51, Jenki said:

@Super_Paulie I used a TMV, and although the spec doesn't say you can get below 30 deg, I managed to get 26deg accurately. 

Any idea what it was @Jenki ? I can see a Reliance one that claims 30°, but if it can't get down to 26/27° then it's a non starter.

[Jenki]

13 hours ago, Super_Paulie said:

Any idea what it was @Jenki ? I can see a Reliance one that claims 30°, but if it can't get down to 26/27° then it's a non starter.

Think it was this. I had this set to 27 Deg from Combi boiler. 

[Super_Paulie]

4 hours ago, Jenki said:

Think it was this. I had this set to 27 Deg from Combi boiler. 

thanks fella, i'll look into it.

[Super_Paulie]

On 02/05/2023 at 13:42, Nickfromwales said:

The flow rate at the combi boiler cold inlet is what pushes hot water out of the taps. As you are "stealing" from the rising cold supply to it, multiple times before it gets to the combi, you will likely see a significant loss in performance for the DHW output. If you run 22mm all the way ( to the last T-off ) and then drop to 15mm > combi, then effectively you have enough capacity in the 22mm pipe to service the "theft" as well as still having sufficient residual capacity to provide adequate cold mains 'potential' at the combi. Any instant water heater should have "cold mains priority" which is either achieved by running a dedicated feed from the stopcock to the appliance, or by doubling the capacity of the single supply pipe.

Just about to put this into action @Nickfromwales, just a thought, which joint is preferable out of the 2 extremely crudely drawn images? Basically 2 different tees, or are both much a muchness?

 

cheers!

[Nickfromwales]

Option 2 lol. That’s referred to as a “22-15-15” tee, or “end and centre’ reducing. 
The spur of the tee is called the centre, so a 22mm centre tee (so you can branch off a straight 22mm pipe run with 15mm pipe) is referred to a 22x22x15 tee, as you call the centre (spur) as the last ‘dimension’. 
If the run to the combi is long, I’d run 22mm pipe most of the way tbh.

[Super_Paulie]

5 hours ago, Nickfromwales said:

Option 2 lol. That’s referred to as a “22-15-15” tee, or “end and centre’ reducing. 
The spur of the tee is called the centre, so a 22mm centre tee (so you can branch off a straight 22mm pipe run with 15mm pipe) is referred to a 22x22x15 tee, as you call the centre (spur) as the last ‘dimension’. 
If the run to the combi is long, I’d run 22mm pipe most of the way tbh.

its maybe 3m from the joint to the boiler, boiler just above loft floor level so the pipe run up the side of the chimney breast in the copper. So a 22-15-15 would surfice, be pretty easy to be fair as i already have all my copper in until the new joint so i can just plug into it.
Alteratively i could break into the copper higher up and convert from 22 to 15 there, but not sure it would make much of a difference?

[Nickfromwales]

7 hours ago, Super_Paulie said:

its maybe 3m from the joint to the boiler, boiler just above loft floor level so the pipe run up the side of the chimney breast in the copper. So a 22-15-15 would surfice, be pretty easy to be fair as i already have all my copper in until the new joint so i can just plug into it.
Alteratively i could break into the copper higher up and convert from 22 to 15 there, but not sure it would make much of a difference?

 

That'll be A-OK