Indirect thermal store?

[echoes]

You could have used a bronze pump and let the gravity supply some of the outlets. Kitchen sink, bath.
Then in a breakdown situation you still have hot water.

Good suggestion - that would have been nice. Sadly the pipe supplying all those outlets is under the finished bathroom floor. Maybe one day...

 

[stonehouse]

Thanks for the photos.

let the gravity supply some of the outlets. Kitchen sink, bath.

Do you mean from the hot water in the cylinder like Bernard Green's arrangement?

What's a bronze pump by the way?

 

[echoes]

Yes, although @bernardgreen 's contraption doesn't need a pump because he's got an internal coil instead.

Bronze pump is needed when the water being pumped is also being drawn off. The constant supply of dissolved oxygen and heat will not be kind to an iron pump.

Or it's what you win for being the third-best plumber in town.

 

[oilboffin]

Hahahahaha ah like it

 

[stonehouse]

Good suggestion - that would have been nice.

Apparently, continuing supply of calcium carbonate is not good. Read this:

 

[echoes]

Apparently, continuing supply of calcium carbonate is not good. Read this:

True, but no worse than a conventional cylinder. And at 60 deg is not so problematic.
Depends how got the store is kept. Solubility of CaCO3 decreases with temperature, as a look inside my kettle will confirm!

 

[stonehouse]

echoes, Does your contraption have a thermostatic mixing valve for combining water coming from the plate heat exchanger with cold water?

 

[echoes]

echoes, Does your contraption have a thermostatic mixing valve for combining water coming from the plate heat exchanger with cold water?

No, that was on my list of possible improvements!
If I heated the store to over 65 deg C, then I would install one to prevent scalding, limescale build-up, and use the heat from the cylinder more slowly.
My cylinder is set to just over 60 deg C, like it was before it's conversion, and operates fine at that setting. Also means my boiler has a chance of condensing more of the time, and less heat loss from cylinder.

 

[stonehouse]

So, this type of thermal store is an outdated design as it was meant to work with pre-2007 boilers?

 

[echoes]

So, this type of thermal store is an outdated design as it was meant to work with pre-2007 boilers?

There are ways of ensuring that a store is heated to a high temperature efficiently with a condensing boiler.

The stored water can be heated directly (no indirect coil) in one long burn.

2 thermostats can be used to get more hysteresis in the heating cycles.

This is starting to push the limits of my current knowledge and experience though.
A heatbank or thermal store is not something I'd particularly advocate over unvented without just cause, but I'm very happy to share my experience of building and using one, which, *so far* has been positive, as well as educational.

 

[stonehouse]

There are ways of ensuring that a store is heated to a high temperature efficiently with a condensing boiler.

The stored water can be heated directly (no indirect coil) in one long burn.

2 thermostats can be used to get more hysteresis in the heating cycles.

This is starting to push the limits of my current knowledge and experience though.
A heatbank or thermal store is not something I'd particularly advocate over unvented without just cause, but I'm very happy to share my experience of building and using one, which, *so far* has been positive, as well as educational.

Thanks. I'll bear that in mind.

However, there's probably no point in changing an old boiler for a new one. Here is a good article:

http://www.telegraph.co.uk/lifestyl...791140/Do-I-need-to-install-a-new-boiler.html

 

[bernardgreen]

Quoting two items from the Telegraph item that Stonehouse linked to

""There is also a problem of water wastage when turning on the hot tap in the kitchen or bathroom, as several litres of cold water might have to run through the heat exchanger before the boiler fires up""

""" Unfortunately, many heating engineers persuade clients to have combi boilers fitted, by telling them they are better or, shockingly, by saying that they are compulsory. I cannot think of any advantages for a homeowner in having a combi boiler rather than a system boiler (apart from in a flat with no room for the water tanks). There are advantages for the heating engineer, however – less pipework, easier, quicker fitting, and therefore a bigger profit.

Not to mention the scrap metal price he gets for disposing of your existing copper hot-water cylinder."""

These two points feature in the conclusions of an investigation into a boiler replacement program ( about 70 properties involved ) commissioned autumn 2016 after tenants found there was no reduction in annual gas bills.

 

[stonehouse]

These two points feature in the conclusions of an investigation into a boiler replacement program ( about 70 properties involved ) commissioned autumn 2016 after tenants found there was no reduction in annual gas bills.

Interesting. And what now?

 

[stonehouse]

Hey echoes,

Would an thermostatic mixing valve be something like this?

https://www.screwfix.com/p/pegler-p...gclsrc=aw.ds&dclid=CLPZxK-ohdgCFVGeGwodlB0PQA

 

[echoes]

Hey echoes,

Would an thermostatic mixing valve be something like this?

https://www.screwfix.com/p/pegler-p...gclsrc=aw.ds&dclid=CLPZxK-ohdgCFVGeGwodlB0PQA

Well, something like that. The only ones I've seen in the DIY sheds (that one included) are intended to be fitted *at* a basin or bath to prevent the hot water from scalding and they are set to about 43 - 46 degrees C.
Now that's not hot enough for a kitchen sink or the hot feed to most showers. A TMV at a store should be blending to about 55 degrees C (which also minimises legionella risks, if I remember rightly).