Two calorifiers

[Robbo]

3 minutes ago, Mike the Boilerman said:

(Both have the neoprene bag inside, I forgot to say.)

I thought the ones for central heating systems didn't have the bag so weren't really suitable for fresh water use?

Edited November 15, 2017 by Robbo

[Bromleyxphil]

4 minutes ago, Mike the Boilerman said:

 

No, they are identical structurally. The difference is in the use to which you are putting them. 

In the world of plumbing the two terms are used interchangeably. Only here in boat world do people seem to draw a distinction. The difference in function is quite subtle.

(Both have the neoprene bag inside, I forgot to say.)

So this pump https://www.mackengineering.co.uk/r3426-344a-24v-triplex-pressure-controlled-pump.html doesn’t need one.  As I said I have now been using one in my camper without any expansion for years.

 

[nb Innisfree]

51 minutes ago, Bromleyxphil said:

Excuse my ignorance but what is the difference between an accumulator and an expansion vessel

Just to to other explanations, when a calorifier heats up the water expands, if there is no closed air space for water to expand into it will push the pressure relief open and water will seep past it. 

[MtB]

16 minutes ago, Robbo said:

I thought the ones for central heating systems didn't have the bag so weren't really suitable for fresh water use?

 

Nope. CH ones definitely have the bag. The bag perishes after about ten years generating a healthy flow of work for people like me!  

This, amongst a load of others, is the main reason sealed system heating systems are a Bad Thing in my personal opinion.

[WotEver]

3 hours ago, Mike the Boilerman said:

sealed system heating systems are a Bad Thing

So are microbore systems. Don’t ask me how I know this...

[David Mack]

9 hours ago, Bromleyxphil said:

Excuse my ignorance but what is the difference between an accumulator and an expansion vessel

If you have a non-return valve on the inlet to your calorifier, then as the water in it heats up and expands it has nowhere to go unless you have an expansion vessel. But if you don't have a NRV then the hot water can expand back into the cold water pipework and use the accumulator for both purposes, with the slight downside that you may get a little warm water out of your cold tap.

[MtB]

5 hours ago, WotEver said:

So are microbore systems. Don’t ask me how I know this...

 

Correct! Best avoided in my opinion. Even if that means selling the house...

[Bromleyxphil]

28 minutes ago, David Mack said:

If you have a non-return valve on the inlet to your calorifier, then as the water in it heats up and expands it has nowhere to go unless you have an expansion vessel. But if you don't have a NRV then the hot water can expand back into the cold water pipework and use the accumulator for both purposes, with the slight downside that you may get a little warm water out of your cold tap.

Must admit I hadn’t thought through the NRV situation both the calorifier and gas heater in the van have a PRV.

thanks

Phil