What energy rating is your HW cylinder?

[Adsibob]

I have an unvented indirect hot water cylinder, 300L made by Telford, called the Telford Tempest. I bought it towards the end of last year.

i was surprised it only has a C energy rating. What rating does your cylinder have?

If I was to fit one of those insulated jackets over it, would this upgrade it to a B? 

[JohnMo]

I made one for mine, used off some vapour control fabric/foil, some left over mineral wool and double sided tape.

 

Made a load of pillow/cushions, shaped to go around the cylinder.  Two layers of vapour control fabric (back to back), double sided tape on 3 sides, fill with mineral wool seal with double sided tape.

 

They can be easily removed if I needed access.

 

Heat exchanger is wrapped in 25mm PIR.

 

Took about an hour.

[Adsibob]

17 hours ago, JohnMo said:

I made one for mine, used off some vapour control fabric/foil, some left over mineral wool and double sided tape.

 

Made a load of pillow/cushions, shaped to go around the cylinder.  Two layers of vapour control fabric (back to back), double sided tape on 3 sides, fill with mineral wool seal with double sided tape.

 

They can be easily removed if I needed access.

 

Heat exchanger is wrapped in 25mm PIR.

 

Took about an hour.

Impressive! What was the energy rating of the cylinder before though, and what do you think you boosted it to with all that insulation?

[JohnMo]

Not sure of the original energy rating.  But it leaked heat quite well.

 

I had a section of the additional insulation off yesterday and you could feel outside of the cylinder hot.  Which you didn't before.  It still looses heat quicker than I want.

[scottishjohn]

8 minutes ago, JohnMo said:

Not sure of the original energy rating.  But it leaked heat quite well.

 

I had a section of the additional insulation off yesterday and you could feel outside of the cylinder hot.  Which you didn't before.  It still looses heat quicker than I want.

that does not suprise me 

If you add insulation to cylinder that will trap any heat loss of the cylinder  between it and your better insulation .

more important is how much heat can you feel on outside of the insulation layer ,

 that is now your heat loss .

so it would be important to make the room all this heating plant is to be very well insulated ,unless you are happy with the heat adding to your background house heating input.

 

 

[ProDave]

I have the Telford Tempest heat pump cylinder so I suspect the same rating as your if I cared to look it up.

 

I find in practice the heat loss is low, no part of the tank ever feels warm to the touch, but I only normally store hot water at 48 degrees so the heat loss in 24 hours will be less than what they state as they assume a much higher storage temperature.

 

What is VERY important with any cylinder is insulate ALL the pipework connecting to the cylinder very well. That means good thick insulation and neat joints that are at least taped so no gaps.  without insulation or with poor insulation you will lose more heat from the connecting pipes than from the cylinder.

[joe90]

Mine is the same as @ProDave above and very low levels of loss.

[Radian]

In my father's house the cylinder was in a built-in cupboard and he cut the full height door half way up and fixed the lower half in front of the cylinder, stable door style. He then filled the void around the cylinder with a large quantity of EPS beads. Pretty much as good as you'd think you could get - but it still made the bedroom it was in too damn hot. Conduction is the isses here. And accessing the pipework.

[JohnMo]

OSO, do A rated cylinders, heat loss about 0.8kWh per 24 HR.

 

[SteamyTea]

5 minutes ago, Radian said:

In my father's house

In mine, there are many mansions 

 

 

You can calculate heat loss the same way that you do for a walk or floor.

U-value x area x temperature difference.

[Radian]

38 minutes ago, JohnMo said:

OSO, do A rated cylinders, heat loss about 0.8kWh per 24 HR.

 

Constant 33.3W loss then. Our C rated Gledhill is 70W loss. Really ought to do something about it.

[PeterW]

So don’t forget these calculations are cylinder loss only, and assume the tank is kept at a constant temperature. In reality the losses are less as the tank cools by usage (and loss) and the bigger emitters are pipework losses. 
 

Also the heat is not “lost”, it is transferred to the air and the house so reduces the heat load in the winter so beware trying to calculate how much it is costing as it’s not simple !!

[Adsibob]

1 hour ago, ProDave said:

What is VERY important with any cylinder is insulate ALL the pipework connecting to the cylinder very well. That means good thick insulation and neat joints that are at least taped so no gaps.  without insulation or with poor insulation you will lose more heat from the connecting pipes than from the cylinder.

Yes, I’m finding that when I run the secondary loop pump, the heat loss is noticeably much more. The loop is insulated, but very badly. Plumber told me only a thin sheath of foam insulation was necessary because he was using buteline pipe for the loop, which being plastic doesn’t conduct heat very well. I believed him and now it’s too late to do much about it. I think I will invest in a couple of Shelley sensors and a Shelley switch and make the secondary loop pump only come in when two taps are walked near to, which are the only two taps where it is really necessary.

 

The room where the cylinder is in is very well insulated and in the loft conversion so already quite warm, but I will wrap it in insulation anyway. I don’t have much space though. Suggestions for variable depth insulation (I have 4cm to 5cm of space on two sides of cylinder but zero on a third side as cylinder right up against the wall, and obviously space tends from 4cm to zero as one gets closer to that join with the wall).

Edited July 24, 2022 by Adsibob

[SteamyTea]

52 minutes ago, Adsibob said:

have 4cm to 5cm of space on two sides of cylinder but zero on a third side as cylinder right up against the wall

Why do plumbers fit them like that every place I have owned has been the same.

 

I lined two sides of my cylinder cupboard with Celotex, then filled the 'corners' with mineral wool. Celotex lid for the top.

Pipe insulation does not have to be pipe shaped. Boxed in mineral wool works just as well, sometimes better.

Thermal losses are not like water leaks, you don't loose a disproportionate extra amount of energy on a tiny length of uninsulated pipe. Unlike a water leak which seems to squirts further the small the hole is.

 

[Adsibob]

I wonder if I could use one of these, but trim it so it fits even though cylinder is touching the wall:

https://www.screwfix.com/p/hot-water-cylinder-jacket-18-x-80mm-x-1219mm/43483

[JohnMo]

Spurred on by this thread, have made an effort to reduce the piping heat losses further.  Covering the hot piping areas in 25mm PIR sheeting (more left overs got rid off) and aluminium tape.

 

Wife saying - your always messing about, don't know why your bothering.

[SteamyTea]

6 minutes ago, JohnMo said:

Wife saying - your always messing about, don't know why your bothering.

Make her pay the bills.

[Ferdinand]

17 minutes ago, JohnMo said:

Spurred on by this thread, have made an effort to reduce the piping heat losses further.  Covering the hot piping areas in 25mm PIR sheeting (more left overs got rid off) and aluminium tape.

 

Wife saying - your always messing about, don't know why your bothering.

I thought it was a Robot out of Arthur C Clarke...

[JohnMo]

Does look a bit like that and very silver.

[SteamyTea]

1 hour ago, Ferdinand said:

I thought it was a Robot out of Arthur C Clarke...

And people still want home automation

 

 

[Spacey73]

I’m still stuck deciding between the largest Sunamp or a 300L super insulated immersion. Have 12k of solar on tap and 20kwh batteries.

Edited July 28, 2022 by Spacey73

[Marvin]

53 minutes ago, Spacey73 said:

I’m still stuck deciding between the largest Sunamp or a 300L super insulated immersion. Have 12k of solar on tap and 20kwh batteries.

Hi @Spacey73

 

Depends on what is driving your decision: Installation cost, space, running cost, demand......

 

Also depends on what your other sources of heat are....

 

It's the winter you want to be thinking about. Are you considering a 300ltr tank because of the amount of hot water you use or thinking of using it as a heat sump. Also in winter how much PV power are you expecting to have excess of to use heating the water? The conundrum here is you could end up with only enough PV power to have a huge tank of tepid water, and so end up using other power to bring it up to temperature  What is the average kWh you expect to produce on each day in January?  We have 5.12kW PV and we produced about 6kWh a day in January, HOWEVER, your amount would depend on the panel slope, the angle in relation to the sun's zenith, the shading by objects and the location and so on.

 

 

 

Hi @Adsibob

Here is my 205ltr tank:

 

PIR in room walls, supersoft around tank, 6mm ply on frame to encase the lot.

 

 

HOWEVER!

 

Any thermostat in the insulation will need to be digital.

 

If I have it right,  this type of immersion heater thermostat relies on a bimetallic switch which relies on a typical room temperature to work:

so incasing it in insulation means it will not work. (I'm sure someone will correct me if I'm wrong)

 

I have used one of these to switch a 20amp relay to turn on the hot water immersion:

 

Note the type of sensor:

 

As you can see only the sensor enters the insulated area:

 

 

Secondly I removed the immersion heater thermostat because that would be effected by the insulation similarly.

 

AND

 

All power cables in the insulation will need to be ducted.

 

Good luck.

 

M

[Adsibob]

@Marvin that's very interesting and useful info. I query though why you did it that way as opposed to buying one of those jackets from screwfix for £13. 

If i did use your method, I will need to change thermostats, which i fear will require draining the whole system.

Also, why is this necessary:

20 minutes ago, Marvin said:

All power cables in the insulation will need to be ducted.

[Marvin]

Hi @Adsibob

 

You can always just chuck a jacket on, as long as you avoid the electric cable and immersion covers. My tank is a simple indirect one, and by the sounds of it yours sounds more complicated. what is it?

 

It's unusual to drain down a tank to replace a thermostat. My buffer tank has pockets in which the probes fit in to. These pockets are a copper or brass tube which separates the space in the pocket from the water so no need to drain down.

 

The electric cable supplying high energy to an emersion will heat up when there is demand and the heat in the cable needs to dissipate which it will not if encased in insulation. 

[Marvin]

Hi @Adsibob

 

A further thought...

 

Going the simple way of jackets, you can put as many as you like around and on top of the tank, so long as you don't cover cables or immersion covers (leaving a clear flow of air to the immersion metal caps) 

 

If the tank is in the corner of a room and there are no cables in the area you can just fill all the gap no problem.  The jackets are just loft insulation stuff wrapped in a plastic covering. You can condense them to squeeze them into gaps. if you fill the gap between the tank and the wall the thermal resistance of the heat coming out of your tank will now include the makeup of the wall so even better. (mine purposely had PIR installed in the wall for that reason).

 

For clarity, the insulation's thermal resistance is measured by it resistance to temperature change and its thickness, however, as I understand it, squeezing two 100mm thicknesses into a 100mm gap will not make it twice as resistant because , as I understand it, the air gaps between the fibres are what cause it to resist thermal change.  Definitely where possible wrap as much around as possible, squeeze thinner where no alternative, and you'll definetly save money in the long run.