Jump to content

Direct/indirect, Vented/unvented Hot Water Cyliders - Help me understand what combinations work.


LeanTwo

Recommended Posts

For a long time I have heated our hot water in a copper cylinder which has two immersion heaters (for our Economy 7 tariff) and an internal coil which is connected to a small boiler in our multi-fuel stove.  We occasionally use the upper immersion to top up hot water during the day.

 

This system has proved flexible and largly maintenance free over the years. However, recently I have seen a ring of water at the base and damp in the ceiling below. So it's time to inspect the base to see if corrosion has occured and fit a new cylinder. This could be combined with relocating a new cylinder to our loft which was suggested on a previous thread that I started.  I need more space in the bathroom.

 

I suppose my current system is both direct (The immersion heaters) and indirect (The internal coil from the multi-fuel stove)?

 

When I am pricing up cylinders there are a plethora of steel cyliners, which are unvented, presumably to build a pressure to move the water around in the absence of an F&E tank?

 

Can cylinders like my current one (Both direct and indirec) be found on the market? Can I provide cold water to all taps from the rising main (so doing away with my large F&E tank?

 

Any explanation of the terms used or what combination of them work would be gratefully received!

…and how could I build my Economy 7 tariff?

 

 

Link to comment
Share on other sites

26 minutes ago, LeanTwo said:

When I am pricing up cylinders there are a plethora of steel cyliners, which are unvented, presumably to build a pressure to move the water around in the absence of an F&E tank?

Yes.

 

26 minutes ago, LeanTwo said:

Can cylinders like my current one (Both direct and indirec) be found on the market?

Yes, all decent cylinders, whether direct or indirect should have the ability to install one or two a back up immersion heaters. Normally these are back up, because most people hear hot water with a gas boiler, and that used to be considerably cheaper than electric. But if the boiler breaks down you hear with the electric immersion heater. Now with all the changes in energy prices, it may be cheaper on certain tariffs to heat with electric at night, I’m not sure.

 

26 minutes ago, LeanTwo said:

Can I provide cold water to all taps from the rising main (so doing away with my large F&E tank?

Yes.

Edited by Adsibob
Link to comment
Share on other sites

@LeanTwo if you speak to Trevor at Cylinders2Go and mention the forum and @Nickfromwales you should get a good deal. Telford allow you to add additional immersions wherever you need them. 

 

The issue you will have wanting to keep the boiler coil is that you need an F&E tank with a boiler stove, or at least a system to stop it overheating - that can be a quench coil or similar. That means your F&E has to be higher than the coil in the tank so bear that in mind. 

Link to comment
Share on other sites

Just swap like for like, I got my cylinder from Trevor at Cylinders2go. Quick delivery to my end of the country.

 

Think about adding secondary insulation around it while the old one is our, makes a big difference. I just stuffed the cupboard with Sheet Foam and mineral wool, and lagged the pipes more.

Link to comment
Share on other sites

Thanks for all of the replies.  I'll contact Trevor.  I have a small F&E tank already.  We have no gas in the village.

 

So what I will check out with Trevor is a tank with an unvented direct (Economy7 immersions) and indirect coil (using my smaller F&E tank raised up) in the loft, heated by the multi-fuel stove.

 

I'm assuming that with the coil located at the bottom of the unvented cylinder and ensuring that the small F&E tank is above the coil level then I should be OK?  Is there a minimum difference in height needed between the coil and F&E tank?

Link to comment
Share on other sites

4 minutes ago, LeanTwo said:

So what I will check out with Trevor is a tank with an unvented direct (Economy7 immersions) and indirect coil (using my smaller F&E tank raised up) in the loft, heated by the multi-fuel stove.

Not sure what the F& E will be used for with an unvented cylinder.

What sort of control is on the stove to stop over temperature?

Link to comment
Share on other sites

On 07/10/2022 at 21:07, Adsibob said:

.

 

On 07/10/2022 at 20:41, LeanTwo said:

Can I provide cold water to all taps from the rising main (so doing away with my large F&E tank?

Yes.

That may depend on your mixers at taps and showers, as some need to balanced pressure wise, cold water will be at couple bar pressure, hot water maybe at 0.5bar with a vented cylinder 

 

Not sure you can connect solid fuel boiler easily or is allowed to be connect to an UVC?

Link to comment
Share on other sites

1 hour ago, JohnMo said:

 

Not sure you can connect solid fuel boiler easily or is allowed to be connect to an UVC?


You can but you need to put a neutraliser in the circuit - I’d assumed there would be one already if there is a tank on the current setup as otherwise you end up boiling any tank. 

Link to comment
Share on other sites

1 hour ago, SteamyTea said:

Not sure what the F& E will be used for with an unvented cylinder.

What sort of control is on the stove to stop over temperature?

 

 

I thought that I would need this for the indirect heating coil from my multi-fuel stove?  I have a small loft F&E tank connected to my multi-fuel boiler at present.  I only have the ash pan door to control the temperature but it does seem to work.  The multi-fuel boiler is just a heat top-up and is quite small.  The main source of heat is my Economy 7 immersion.

 

1 hour ago, JohnMo said:

That may depend on your mixers at taps and showers, as some need to balanced pressure wise, cold water will be at couple bar pressure, hot water maybe at 0.5bar with a vented cylinder 

 

Not sure you can connect solid fuel boiler easily or is allowed to be connect to an UVC?

OK, thanks for the heads up on balancing taps and solid fuel stoves connected to UVCs.  I will mention these to Trevor at Cylinders2Go.  I could always go for a vented system but I was attracted to the idea of doing away with the larger F&E tank that I have in my loft.

Link to comment
Share on other sites

A thermal store is an option. A combi store unit would allow you to get rid of the F+E and keep the stove boiler whilst moving to a pressurised hot water system. No g3 requirements either. 

 

A simple direct UVC would work but you'd need to get rid of the stove boiler. 

 

A bit left field but an exhaust source heat pump would be a good option to consider too. Remove the boiler from the stove. excess heat generated by the stove could then be removed from the air to heat the water at 3:1 for the use of your electricity. @Thedreamer does this happily i understand. 

 

 

 

 

Link to comment
Share on other sites

Very happy with our system. It works for our circumstances.

 

We are in a self build finished in 2020. I heat the house with a centrally place wood stove surrounded by dense concrete blocks. 

 

Our hot water comes from a Joule aero exhaust heat pump.

 

 

Link to comment
Share on other sites

@LeanTwo

Are you looking to improve something i.e. flow rate on shower, or just looking to change an old broken system?

 

There is little difference between a properly set up vented or unvented system thermally (though others will argue against this).  The physics is the same i.e. pump x amount of water at y°C will be your power deliver, store x amount of water at Δy°C is your energy.

Link to comment
Share on other sites

On 09/10/2022 at 21:37, Thedreamer said:

We are in a self build finished in 2020. I heat the house with a centrally place wood stove surrounded by dense concrete blocks. 

Just curious about this. Do you effectively have a giant stack of concrete blocks in the middle of your home acting as radiators built into the wall? Sounds really cool but just trying to imagine it.

Link to comment
Share on other sites

2 hours ago, Adsibob said:

Just curious about this. Do you effectively have a giant stack of concrete blocks in the middle of your home acting as radiators built into the wall? Sounds really cool but just trying to imagine it.

 

Yes, pretty much. The blocks are the proper heavy dense concrete ones.

 

Around now to March I heat the house with sticks (mostly fast growing alder) that I collect. I do also burn some home grown super dry spruce as well. It takes very little to heat the house in the evening and the house holds the heat until the next evening.

 

I achieve a really greet COP on the exhaust air source heat pump as it does not vary much compared to an external heat pump heating water which can be less efficient in the winter.

 

I don't have PV panels, but with the government rebate my total energy bills will be a couple of £s for the next six months. 

 

P1170016.JPG

 

 

20200910_182932.thumb.jpg.50b9ae8ba13817006cbaca281a45b6c2.jpg

 

Link to comment
Share on other sites

Very cool and lovely looking house you have there.

My only concern would be that the living room where the stove is will always be warmer than other places, but I guess that doesn't matter too much given cooking appliances in the kitchens will help bring the temp up in there when you're cooking and you want the bedrooms cooler anyway. But what about the bathrooms? Do you have any towel rails? Doesn't the tiled floor get very cold?

Link to comment
Share on other sites

16 hours ago, Adsibob said:

Just curious about this. Do you effectively have a giant stack of concrete blocks in the middle of your home acting as radiators built into the wall? Sounds really cool but just trying to imagine it.

 

There was a Grand Designs project that used a full height inside wall as a massive storage heater on the similar "chimney in the middle of the house to heat all directions idea". It may have been slate or stone.


A quick search and I can't locate the exact project.

Link to comment
Share on other sites

1 hour ago, Ferdinand said:

 

There was a Grand Designs project that used a full height inside wall as a massive storage heater on the similar "chimney in the middle of the house to heat all directions idea". It may have been slate or stone.


A quick search and I can't locate the exact project.

 

Got a feeling it was this one? https://www.granddesignsmagazine.com/grand-designs-houses/thatched-cottage-new-forest/

At least, that house was rebuilt after a chimney fire so they made a big deal about the robustness of the new chimney. But I thing there may have been another episode with similar idea.

 

 

 

Link to comment
Share on other sites

On 07/10/2022 at 21:07, Adsibob said:
On 07/10/2022 at 20:41, LeanTwo said:

Can I provide cold water to all taps from the rising main (so doing away with my large F&E tank?

Yes.

 

One thing to keep in mind is any mixer taps / shower TMVs should have their cold feed come off the same pressure reducing valve ("cold water control group" or multibloc valve) that feeds into the UVC. 

But aside from the kitchen main they probably already all feed off the old large cold water tank in the loft anyway, so should be easy to reroute these from your UVC if that's going to be in the loft.

Link to comment
Share on other sites

15 minutes ago, joth said:

 

Got a feeling it was this one? https://www.granddesignsmagazine.com/grand-designs-houses/thatched-cottage-new-forest/

At least, that house was rebuilt after a chimney fire so they made a big deal about the robustness of the new chimney. But I thing there may have been another episode with similar idea.

 

 

 

 

The one I'm thinking of had a huge feature stone wall bisecting the house, and iirc it had a GSHP heating it up.

 

But I am not at all sure without finding it.

Link to comment
Share on other sites

9 hours ago, Adsibob said:

Very cool and lovely looking house you have there.

My only concern would be that the living room where the stove is will always be warmer than other places, but I guess that doesn't matter too much given cooking appliances in the kitchens will help bring the temp up in there when you're cooking and you want the bedrooms cooler anyway. But what about the bathrooms? Do you have any towel rails? Doesn't the tiled floor get very cold?

 

Thanks for your kind words.

 

When we considered the space I didn't want a living room, but to try and incorporate the concept of a 'great room'.

 

This allows the heat not to over the power the space, which is the problem when people put stoves in modern self builds.

 

Yes, the kitchen warms itself from the cooker etc.

 

The bathroom is formed behind the the stove blocks, so benefits from heat.

 

We do have towel heaters in both the bathroom and our ensuite which can be utilised if needed, but rarely this happens.

 

I have LVT on the floor which is warmer to the foot compared to tiles, so no underfloor heating.

 

Our aim was to construct a home that would cost £500 or less a month to run (Mortgage, heating, council tax, telephone, insurance). 

 

We want to live a life not controlled by debt or the whim of a dictator.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...