New house hot water woes

[Doggit]

4 minutes, ouch, that's a lot of wasted water. Okay, can you insulate all the pipes on the recurculating system. A 2nd 150Ltr tank would be cheaper than installing a new 300, but would take up more space. Have you tried running 2 showers at once to see the effect.

 

[AdvanceHelpline]

With two bar dynamic you would expect a much higher flow rate than you have got which indicates restricted flow somewhere. See earlier comments regarding possible restrictions in your circuit.

 

[zooankski]

Thanks for the responses so far. I am waiting for a further plumber to come and take a look and give me an opinion.
In regards to the secondary circuit, the water is controlled from a dual channel Honeywell ST699 programmer. The heating channel is not used as underfloor heating is a separate Uponor system.
Could i simply wire the bronze pump in to this channel and set it to come on 10 minutes before the water and 10 minutes after? No idea if the programmer can switch a pump load safely.
Also if i added a stat then would this be checking the loop temp return?
Both plumbers so far have had different ideas, one opting for a single larger tank and accumulator and one opting for a second 150 tank and 2 accumulators.
I will provide all the details when i have them and try and make an informed decision on the best way forward.
I did note that all the pipework spanning the house appears to be 15mm poly.
I have no problem upgrading what i can see to 22mm although wouldn't the step down back to 15mm defeat any benefit? as i have no way of access to pipework dropping down in to the walls (to showers etc)

 

[bernardgreen]

Forgot to mention that with a recirculating system,~~~~~, but I'm not convinced on them

They are fine in hotels where cost of heating is offset by the cost of the room

Small indirectly heated hot water cylinders at points of delivery can be efficient in houses with long distances between places with hot water taps.

Either feed with cold water ( requires cylinder to be large enough to supply the entire need ) or feed with hot water from the boiler ( cylinder only has to hold enough hoter water to supply the need until hot water from the boiler reaches the cylinder.)

 

[Dan Robinson]

So he has to fit a load more controls , primary pipe work , cylinders , secondary pipe work . . . . . When a single slightly larger cylinder is needed and a little warranty cable and a pipe stat ?


You truly are an idiot Bernard .

 

[bernardgreen]

Depend on how much water can be wasted before the hit water reaches the tap

 

[zooankski]

So today i was woken up after my night shift by a Cambridge water engineer. He was responding to my enquiry regarding a record of what supply size the house was fitted with.
He had no information on that although we have worked out that it is 32 mm to the garage and t'eed off to the house in 25 MDPE.
The garage has a supply as it has been designed to be converted in the future (which won't happen!)
Anyway, the pressure at the garage and house is 2.2-2.4 bar, and flow rate at the unrestricted 22mm output i put in for a water softener is over 25l/min using his company weir gauge.
That is nice to know as i have bee thinking about accumulator installs etc.
Would i be right in thinking that the flow to showers etc is basically being hampered by the fact that the house is plumbed in 15mm barrier pipe from end to end?
Would this be improved by changing to 22mm for as much of each run as possible bearing in mind i will not be able to access pipe work in walls which is 15mm?
I guess the secondary circuit could stay as 15mm?
Regarding the lack of hot water, i am a bit limited by space where the current 150l Santon tank is. A second 150l Santon tank could be a possibility?
There is a space between 2 rafters although it would be tight where the rafters slope past with a 5mm clearance (which would extend past the lower 20 cm of a tank). Above the height that the rafters go past would be unobstructed although limited in height above 1.2 meters.
Would a 5mm gap only around the lower 20cm of the tank be an issue with expansion etc?
Another option might be a horizontal tank? never even knew these existed until tonight! does anyone have experience of these?

 

[Dan Robinson]

by the fact that the house is plumbed in 15mm barrier pipe from end to end?

To quote the dog... oooooooh yess.

I guess the secondary circuit could stay as 15mm?

Yes, but if it is not copper then you could be in trouble....

the current 150l Santon tank

Remind me again (so I don't have to trawl through all the bullshcit from the resident numpties) how big the place is and how many people are there and what boiler it is.

There is a space between 2 rafters

Physical space might be less of an issue - think of the weight!

Would a 5mm gap only around the lower 20cm of the tank be an issue with expansion etc?

You lost me there.

Another option might be a horizontal tank?

Not unless you are very desperate.