Hot water recirculation pump good idea? Grundfos?

[bernardgreen]

Religion.

Pope work or Pipe work are but a slip of the finger apart.

 

[dilalio]

Pope work or Pipe work are but a slip of the finger apart.

Careful Bernie, the Catholic Church is in enough trouble as it is!

 

[bernardgreen]

the Catholic Church is in enough trouble as it is!

An Italian plumber........? Saving all the VAT he can......?

 

[bernardgreen]

But getting back on topic.

Sensing flow and return temperatures in and ajacent to the pump does allow for a system that can be fitted in the plant room and avoids the need to run a cable to a sensor at the furthest tapping point(s)

 

[Dan Robinson]

But getting back on topic.

Sensing flow and return temperatures in and ajacent to the pump does allow for a system that can be fitted in the plant room and avoids the need to run a cable to a sensor at the furthest tapping point(s)

As I implied in my previous post - that is the last place to put the only sensor on a system.

 

[Yorkshirebloke]

That made for some interesting reading, thanks Dan etc.
This is getting a bit daft now Dan, I'm basically fitting your system. Send me a shopping list! Haha.

Ok a question about the return system....
If the return pump (grundfos comfort) is not running, the system will still allow the hot water to flow to the taps right? It will I presume just be like a 'normal' system and take some seconds for the hot water to appear at the tap.

 

[bernardgreen]

last place to put the only sensor on a system

Simple question. where is the hot water needed. ?

All around the loop or just along the side of the loop that takes the hot water to the tap.

Why fill the return side with hot water ?

And think about this.....Could the return side be a much smaller diameter pipe. ? The return pipe only has to carry enough water to allow the flow side to become filled with hot water as far as the furthest tap. Once the flow side has hot water as far as the furthest tap the circulating pump can shut down until the water has cooled enough to require a bit more circulation.

 

[JimCrow]

As for Teeing into the cold feed, does that not waste a smidge of energy? I was lead to believe that returning the slightly cooler water towards the top of the tank would save energy rather than pitting that back into the bottom. Is this noticeable?
On the Joules tanknits got the outlet/inlet already there, should I make use of it or plumb it back into the cold feed with a swept T and a NR valve.

Use the secondary return tapping you already have on the cylinder, a secondary return connection should not be below a third down the side of any hot water cylinder vented or unvented.

 

[Dan Robinson]

FFS Bernie....


Legionnaires

 

[Dan Robinson]

a secondary return connection should not be below a third down the side of any hot water cylinder vented or unvented.

Why?

 

[lostinthelight]

Why fill the return side with hot water ?

And think about this.....Could the return side be a much smaller diameter pipe. ? The return pipe only has to carry enough water to allow the flow side to become filled with hot water as far as the furthest tap. Once the flow side has hot water as far as the furthest tap the circulating pump can shut down until the water has cooled enough to require a bit more circulation.

I am a little confused about the return pipe size.
I've done a fair bit if research on cylinders and pumps lately and some of the former have a return tapping for 15 mm pipe and say in the manual to use 15 but the answer I got from grundfos was pipe should be no smaller than 20mm
litl

 

[Dan Robinson]

Google has just entered meltdown

 

[bernardgreen]

Legionnaires

could develop ( breed ) in any pipe that contains luke warm water. So it will develop in any hot water pipe that has been allowed to cool down because the tap at the end hasn't been used for a few hours. But it doesn't, the secret is in the word breed, if the hot water in the cylinder was hot enough to kill any bacteria then there can be no viable bacteria in the pipe work so hence no breeding can happen when the pipe work cools down.

use 15 but the answer I got from grundfos was pipe should be no smaller than 20mm

Returning water arriving at the pump through a small bore return pipe will have lost more heat ( per volume of water ) than would be lost if the return pipe was larger diameter. As the Danfos system uses the temperature of the returning water in it's processing a reduction in temperature along the return pipe will result in incorrect processing.

 

[Dan Robinson]

could develop ( breed ) in any pipe that contains luke warm water. So it will develop in any hot water pipe that has been allowed to cool down because the tap at the end hasn't been used for a few hours. But it doesn't, the secret is in the word breed, if the hot water in the cylinder was hot enough to kill any bacteria then there can be no viable bacteria in the pipe work so hence no breeding can happen when the pipe work cools down

Twaddle as usual

 

[bernardgreen]

Twaddle as usual

Tell that to the microbiologists and see what they say.