A Energy Rated unvented cylinder

[Nick Laslett]

59 minutes ago, Nick Laslett said:

I’ve found an ‘A+’ rated UVC. Vitocell 300-V 200, seems a bit pricey compared to the OSO and Panasonic, also not appropriate for ASHP. As far as I can see as it does not have the longer internal coil. The 200L model has a standing heat loss of 0.75, which is better the the Sunamp UniQ9, which is their 200L equivalent. 
 

https://viessmanndirect.co.uk/Catalogue/Commercial-Cylinders/Vitocell-300-V-Type-EVIA-A-Single-Coil/Vitocell-300-V-200-litre-EVIA-A-White-Z016794

 

Not sure how editing works, so had to quote my post. 
 

Viessmann in their ASHP brochure  indicate that their UVC is appropriate for heat pumps, but on the direct website they offer the OSO Delta Geocoil. The rating for their 300L tank is similar to the OSO, only the 200L & 160L have the A+. I believe that what makes an UVC more suited to heat pumps is the length of the internal coil. In the 200L OSO Delta Geocoil the primary heat exchanger surface area is 1.4m2, this is from UK manual. I could not yet  find these details in the Viessmann UVC documentation. 

[PeterW]

2 hours ago, Nick Laslett said:

In the 200L OSO Delta Geocoil the primary heat exchanger surface area is 1.4m2, this is from UK manual. I could not yet  find these details in the Viessmann UVC documentation. 

That is tiny - in the Telford HP UVC Range it is 3.3sqm as standard. 

[Nick Laslett]

2 hours ago, PeterW said:

That is tiny - in the Telford HP UVC Range it is 3.3sqm as standard. 

What is more important the standing heat loss or size of heat exchanger?
 

i get than one effects how long it takes to heat up and the other how long it holds the heat. The Panasonic only had a 1.5kw immersion, which seems equally tiny. Does the low standing loss off set the slow heat uptake?

[Nick Laslett]

This thread also discusses coil length for HP.

 

https://forum.buildhub.org.uk/topic/5510-help-me-find-my-hot-water-cylinder/

 

If I’m reading it right, there didn’t seem to be any firm conclusions. 
 

*I have levelled up and gained ability to edit my posts. Thank you forum gods. 

Edited July 5, 2020 by Nick Laslett

[ProDave]

You will see from that thread, I chose the Telford HP cylinder with the large area input coil.

 

The large area input coil is important for use with a heat pump to get good heat transfer into the tank from the input water that is not much hotter than the target temperature.

 

Standing heat loss is a separate issue, though in an ideal world you would find someone making a cylinder with a high area input coil and A rated insulation (let us know if you do)

[Dreadnaught]

On 03/05/2020 at 14:35, joth said:

They do list a UK direct sales info so I might shoot them an email/call

 

@joth, did you ever get a reply from OSO about direct sales?

[Nick Laslett]

2 hours ago, ProDave said:

You will see from that thread, I chose the Telford HP cylinder with the large area input coil.

 

The large area input coil is important for use with a heat pump to get good heat transfer into the tank from the input water that is not much hotter than the target temperature.

 

Standing heat loss is a separate issue, though in an ideal world you would find someone making a cylinder with a high area input coil and A rated insulation (let us know if you do)

I have a feeling that standing heat loss might be more important over the long term than coil length. These Telford’s appear to be ‘C’ rated according to the ERPs on their website. They loose double the amount of heat compared to the Oso, on a 300L UVC, 2.32kwh/24hrs vs 1.18kwh/24hrs according to the details here. 
 

https://www.tdlonline.co.uk/Heating/Hot-Water-Cylinders/Telford-Stainless-Cylinders/Telford-Tempest-Cylinders-Heat-Pump-Coil/6134-/Telford-Tempest-300-Litre-with-Heat-Pump-Coil-33sqm-TSMI300HP

 

To be honest, I have no skin in this game. Until 2 weeks ago I was going to use a Sunamp UniQ12 for my DHW. I don’t need to make a decision on this issue for at least another 8 months. I only started reading about UVCs because my M&E person rubbished my Sunamp plan because he felt they were better suited to smaller properties. I especially enjoyed reading newhome’s thread about her Heat Bank and was glad that PeterW and NickfromWales were able to help her out. 

I think many people still find it difficult to understand what they need to consider for their Space Heating and DHW, adding UVC coil length as another factor is not going to help. 

 

 

 

[ProDave]

My Telford does not lose enough heat to cause an over heating issue, even in summer.  At only 48 degrees water temperature, I suspect the real heat loss is less than 2.3kWh in 24 hours.  And remember for half the year, that "heat loss" is just helping to heat the house and we don't have much in the way of actual heating upstairs so is quite probably beneficial.  I suspect a lot more heat loss is caused in many cases by poorly lagged pipes connected to the cylinder.  Note the pictures of my cylinder in the other thread are before all the pipe insulation got fitted.

[PeterW]

3 hours ago, ProDave said:

Standing heat loss is a separate issue, though in an ideal world you would find someone making a cylinder with a high area input coil and A rated insulation (let us know if you do)

Yep I know one ..! 
 

Newark Copper Cylinder will make whatever you want with whatever thickness insulation you ask for. Only reason I didn’t use them was because we got such a good deal via Cylinders2Go
 

 

[Russell griffiths]

So I know nothing about this, but could you make a plastic bag that is a tight fit around the cylinder, put the cylinder inside and fill it up with spray foam creating an extra layer of insulation. 

 

Is it that simple, what about all the pipe connections. 

[joth]

2 hours ago, Dreadnaught said:

 

@joth, did you ever get a reply from OSO about direct sales?

They distribute via a long of different plumbing merchants so recommend going there, and likely get discount off list price:

" There are many in your area HBS Heating & Bathroom Supplies, Tucker French, Beggs & Partners, James Hargreaves are all independent plumbing & heating merchants, alternatively PlumbCity, Plumbase, City Plumbing Supplies, Wolseley or Graham Plumbers Merchants who are all national plumbing & heating merchant chains to name just a few."

 

In the end it makes much more sense for me to purchase it via the guy installing the ASHP too, as that way I'll pay 5% VAT rather than 20%.  Happily I'd already  gone through all the details with OSO sales office, so when my ASHP guy contacted them directly they already knew the project and what I wanted so put him straight onto a preferred merchant who they knew would do a good prices and arrange delivery direct to site. All done via sales.uk@oso-hotwater.co.uk, super helpful folks. I'll of course withhold final  judgement until its installed and working, but so far I'm quietly optimistic this will be spot on for us.

 

[jamieled]

2 hours ago, ProDave said:

My Telford does not lose enough heat to cause an over heating issue, even in summer.  At only 48 degrees water temperature, I suspect the real heat loss is less than 2.3kWh in 24 hours.  And remember for half the year, that "heat loss" is just helping to heat the house and we don't have much in the way of actual heating upstairs so is quite probably beneficial.  I suspect a lot more heat loss is caused in many cases by poorly lagged pipes connected to the cylinder.  Note the pictures of my cylinder in the other thread are before all the pipe insulation got fitted.

I would agree with this. We have just installed an oso cylinder and the only bit of it that feels warm (with water at 65) is the hot water pipe coming out the back. The cylinder itself doesn't feel much above room temp.

[Nick Laslett]

I found this piece of marketing from the MD of Oso. 
 

“A 300 litre Delta loses only 3.5°C in 24 hours”

https://www.plumbingtrademagazine.co.uk/blog/OSO-Hotwater
 

How true or relevant this is I have no idea. But I was looking for this kind of data to understand what kind of heat loss we should be expecting. I hope others find this useful, but please if this is a fantasy data point because of how heating systems really work, please feel free to make corrections.

 

 

 

 

[PeterW]

1 hour ago, Nick Laslett said:

I found this piece of marketing from the MD of Oso. 
 

“A 300 litre Delta loses only 3.5°C in 24 hours”

https://www.plumbingtrademagazine.co.uk/blog/OSO-Hotwater
 

How true or relevant this is I have no idea. But I was looking for this kind of data to understand what kind of heat loss we should be expecting. I hope others find this useful, but please if this is a fantasy data point because of how heating systems really work, please feel free to make corrections.

 

That sounds about right - 1.225kw was what I calculated it to. Telford will lose about 7.2c in the same 24 hour period. 
 

An additional 1.2kwh of heat per day at CoP 2.5 is about £15 a year in additional electricity or £350 over the 25 year life of the cylinder. 

 

 

[Vijay]

4 hours ago, Russell griffiths said:

So I know nothing about this, but could you make a plastic bag that is a tight fit around the cylinder, put the cylinder inside and fill it up with spray foam creating an extra layer of insulation. 

 

Is it that simple, what about all the pipe connections. 

 

wondered the same thing

[JOE187]

I added 50mm celotex to top  and multifoil wrap insulation to 255 UVC  and insulated all pipes and pressure releif valve! 

  Now minimal heat loss  over 24hrs!