Heat and hot water cylinder vs Vaillant Arastor

[anonymous]

So this is only vaguely related to energy storage, in the sense that heat / water is stored 

 

There's this company 

 

https://heatandhotwatercylinders.co.uk/works-with-octopus-energy/

 

Their cylinders work with Octopus agile, after talking to them and they also store heat as well as water, which helps. That, and they can be put in "now" given they're able to work with gas boilers too 

 

It basically stores that energy at a 1:1 ratio ie: the COP is 1

 

The Vaillant Arastor is a "heat pump hot water heater" which doesn't store heat but it does store water. The cylinder pulls in air from it's surroundings and on paper, the COP is 3.3

 

Given this would be inside the house, it means that the COP probably will be around 3 on average as realistically, the average house doesn't fall below 5C even with the heating off. 

 

What the Arastor doesn't however do is store heat. It also doesn't "work with Octopus"  I'm not sure if you can put this in "now" too ie : by adding something in now, you can stage your implementation a bit which is a bit nicer on the wallet. I guess you could also get a heat battery alongside the Arastor but that just adds costs and complexity 

 

Which would you go for and why? 

 

[Dillsue]

If the heat and hot water cylinders 'work' with the agile tariff then that would be quite a complex controller that can access the published half hourly rates and run the heat pump whenever youve configured it to run. Is that what it does? If thats a 3rd party controller then it will likely work with any DHW cylinder

 

The Arostor stores hot water like any DHW store. It would need a colossally big heat pump to supply hot water on demand without storing any hot water.

 

When you talk about COP and the Arostor being within your house remember that if you dont duct the heat pump to outside, all the heat put into the store will have to come from within the house which will cool the house. 

[anonymous]

49 minutes ago, Dillsue said:

If the heat and hot water cylinders 'work' with the agile tariff then that would be quite a complex controller that can access the published half hourly rates and run the heat pump whenever youve configured it to run. Is that what it does? If thats a 3rd party controller then it will likely work with any DHW cylinder

 

The Arostor stores hot water like any DHW store. It would need a colossally big heat pump to supply hot water on demand without storing any hot water.

 

When you talk about COP and the Arostor being within your house remember that if you dont duct the heat pump to outside, all the heat put into the store will have to come from within the house which will cool the house. 

 

I imagine that the Arostor does indeed store the hot water too, which might mean that I could get it working on gas too? 

 

I guess I would also need a duct 

 

I believe you're right RE: the "heat and water" cylinders, so the Arastor would be cheaper still? Given the COP

 

I've since seen this 

 

 

And I'm not sure if the Joule stuff would be any better? Also I guess again the issue is that it's not a heat store, unlike the "heat and hot water cylinder" 

[JohnMo]

So an unvented thermal store. Hidden behind a lot of flowery talk. And a time of use tariff.  To have any useful energy for CH you would need a big cylinder.

 

[anonymous]

3 minutes ago, JohnMo said:

So an unvented thermal store. Hidden behind a lot of flowery talk. And a time of use tariff.  To have any useful energy for CH you would need a big cylinder.

 

Ie: that's the "heat and hot water" cylinder thing? 

 

So I may as well explore heat pump water heater cylinders line the Arastor / Joule instead? And then also some form of heat battery? 

[ProDave]

When I read the rather wooley description I thought "ah it's just a thermal store"

 

But a thermal store is actually not the best match to an ASHP.

 

I would personally steer clear as I don't like people trying to sell me something with a lot of waffle and obscurity about what it actually IS you are buying.

[anonymous]

28 minutes ago, ProDave said:

When I read the rather wooley description I thought "ah it's just a thermal store"

 

But a thermal store is actually not the best match to an ASHP.

 

I would personally steer clear as I don't like people trying to sell me something with a lot of waffle and obscurity about what it actually IS you are buying.

Thanks. So I may as well get the Arastor instead? 

[Dillsue]

54 minutes ago, anonymous said:

Thanks. So I may as well get the Arastor 

How are heating the house?

[anonymous]

12 hours ago, Dillsue said:

How are heating the house?

Currently it's gas by the combi boiler 

 

I intend to get rid of gas eventually however 

[Nickfromwales]

16 hours ago, anonymous said:

And then also some form of heat battery? 

A heat battery supplier I am familiar with is suffering multiples of failures of their, now eye-wateringly expensive, units. I've received pictures from two clients since xmas who have had failures with their units and damage done to their property. One is "not on his first replacement unit"...  

 

A Telford / other unvented cylinder is cheap, simple and very reliable, and all of these will "work with Octopus"  Contact Trevor at cylinders2go and mention my username and the forum and he will look after you on a price for a cylinder. If you wish to charge this with cheap energy in a short window, you can ask Trevor to fit multiple immersion heaters into this so you can heat it very quickly ( to match half-hour pockets of cheap rate electricity etc ) so can all be done with one unit, very simply, and very reliably. Reliability is the key here, as the heat batteries are, unfortunately, dropping like flies ( from the feedback that I'm receiving.anyways! ).

[anonymous]

14 minutes ago, Nickfromwales said:

A heat battery supplier I am familiar with is suffering multiples of failures of their, now eye-wateringly expensive, units. I've received pictures from two clients since xmas who have had failures with their units and damage done to their property. One is "not on his first replacement unit"...  

 

A Telford / other unvented cylinder is cheap, simple and very reliable, and all of these will "work with Octopus"  Contact Trevor at cylinders2go and mention my username and the forum and he will look after you on a price for a cylinder. If you wish to charge this with cheap energy in a short window, you can ask Trevor to fit multiple immersion heaters into this so you can heat it very quickly ( to match half-hour pockets of cheap rate electricity etc ) so can all be done with one unit, very simply, and very reliably. Reliability is the key here, as the heat batteries are, unfortunately, dropping like flies ( from the feedback that I'm receiving.anyways! ).

Is that heat battery vendor one that has both a lots of amps, and uses the sun? 

 

I guess the unvented cylinder can be used in conjunction with an Arastor? Also fwiw the architect I'm talking to has suggested that the Arastor should go outside 

 

I guess that unvented cylinder also works with Eddi where they divert power from solar to it instead of going to the grid? 

Edited March 2, 2023 by anonymous

[Dillsue]

2 hours ago, anonymous said:

I guess the unvented cylinder can be used in conjunction with an Arastor? Also fwiw the architect I'm talking to has suggested that the Arastor should go outside 

 

I guess that unvented cylinder also works with Eddi where they divert power from solar to it instead of going to the grid? 

If you put the Arostor outside youll have big losses year round particularly in the winter as the cylinder isnt particularly well insulated. What's the Architects rationale for putting it outside when theres a ducting kit available for the heat pump?? 

 

Any cylinder with an immersion can work with an Eddi.

 

If you are looking to ditch gas, how will you heat the house then?? Aside from A2AHP, whatever you heat with will likely be able to heat the hot water so are you sure you want the expense and complexity of a heat pump dedicated to just DHW??

[anonymous]

2 hours ago, Dillsue said:

If you put the Arostor outside youll have big losses year round particularly in the winter as the cylinder isnt particularly well insulated. What's the Architects rationale for putting it outside when theres a ducting kit available for the heat pump?? 

 

Any cylinder with an immersion can work with an Eddi.

 

If you are looking to ditch gas, how will you heat the house then?? Aside from A2AHP, whatever you heat with will likely be able to heat the hot water so are you sure you want the expense and complexity of a heat pump dedicated to just DHW??

Really? I thought you still need a kind of cylinder for an A2AHP? 

 

They've said 

 

"The Arostor can be vented into the room but, preferably it would go to outside. Our concern with room venting would be efficiency and also potential issues around the MVHR system. This would of course be explored in detail to see the overall benefits between options."

[Dillsue]

A2A cant heat your DHW but you don't necessarily need a cylinder with A2A as you can have instantaneous water heaters.

 

From the Architects comments you posted, I read it that the architect is saying the vents need to go outside, not the Arostor itself!!!

[Nickfromwales]

10 hours ago, anonymous said:

Is that heat battery vendor one that has both a lots of amps, and uses the sun? 

Yup. I'm just tired now from writing their name and the word fcuked in the same sentence tbh. Apparently, the boneyard at their HQ is "considerable".

 

8 hours ago, Dillsue said:

What's the Architects rationale for putting it outside when theres a ducting kit available for the heat pump?? 

The architect is a buffoon.

 

3 minutes ago, Dillsue said:

From the Architects comments you posted, I read it that the architect is saying the vents need to go outside, not the Arostor itself!!!

Still a buffoon. Because :-

 

5 hours ago, anonymous said:

They've said 

 

"The Arostor can be vented into the room but, preferably it would go to outside. Our concern with room venting would be efficiency and also potential issues around the MVHR system. This would of course be explored in detail to see the overall benefits between options."

How the feck can you vent stone cold air into the room that you are 100% reliant for to glean input heat from??? FFS?!? The guy is one brain cell up from a turnip. He's just invented "perpetual electric bill". Je-sus.  

[Dillsue]

17 hours ago, Nickfromwales said:

The architect is a buffoon.

 

Still a buffoon. Because :-

 

How the feck can you vent stone cold air into the room that you are 100% reliant for to glean input heat from??? FFS?!? The guy is one brain cell up from a turnip. He's just invented "perpetual electric bill". Je-sus.  

The architect is echoing whats in the Arostor manual!!!