What type of hot water system to have?

[worms]

Running off the hot water will certainly do the trick, though it's not exactly a fail-safe system. Especially after a couple of glasses of wine in a comfy chair in front of a nice warm fire. :wink:

In my experience, the noise of water boiling in the pipes is enough to pretty quickly get you out of the comfy armchair!

Once had an oil stove that used to do this (faulty solenoid in the by-pass circuit) and the way it was plumbed resulted in the boiling water overflowing back into the header tank, which also fed the toilet cistern, giving an interesting hot flush! It also eventually melted the ball valve! Fun times!

 

[Owain]

Surprisingly not all large storage cisterns/tanks are made to accept hot water and can sometime buckle and swell out as a result of boiling water in them. An added risk is, if when the tank was installed, the installer did the old trick of heating up a length of copper pipe to push into the tank to make a hole for the tank connectors. This somehow changes the makeup of the material used to form the tank and it will split at this point. The effect of all this is that you now might have 50 gallons of near boiling water waiting to come through the ceiling.

In fact, a baby was killed a few years ago when this happened, although in that case it was due to a failed immersion heater thermostat. Immersion heaters now have a secondary overheat 'stat with a manual reset.

 

[Feltwell]

8Kw works fine for us. But I fitted a booster pump inline to the cold supply to the bathroom to increase the gravity pressure.
It also means it takes priority over anyone else in the house who may be trying to draw water. No more shrieks from the bathroom as the shower flicks from boiling hot to cold!

That's not a bad idea. Feltwell Towers suffers greatly from 3 small children who inevitably want to go to the loo whilst I'm having a shower. We have 3 toilets, so I'm not disturbed mid-shower as they go to another room, however as soon as they flush the loo the water pressure drops, the cut-out on the shower engages and it goes freezing cold. You have to turn the shower off, wait for the toilet cistern to stop filling, then re-start the shower.

This happens generally twice whilst I'm having a shower, more so if I'm running late for work of course. It's generally timed perfectly for when you have shampoo in your hair and are just about to rinse it out.

Our water pressure is OK so I'm not sure if I'd be better off running a seperate feed just for the shower only from as close to the rising main as possible (we have a water softener so it would need to be from the outlet from there) and if that would work - or is a booster pump the way to go?

 

[steveb]

I went for electric panel heaters - although I would have seriously considered mains gas if it were available in the hamlet.

similar heat load to you Zebra, I have the sap calcs somewhere but a small house up to "modern" insulation standards doesn't need much heat. We have a wood burning stove and panel heaters in three rooms - and similar miserly tastes

the wood stove heats up the living room (the heat doesn't move around the rest of the house as much as we expect) and the other stoves take the chill off the kitchen and bedroom - they're 1.25 kW each and used for about an hour a day.

electric panels are slim, cheap to install, cheap to maintain, have no moving parts or water and very controllable, but expensive to run if you need any significant heat out of them - we used Nobo series 8 panels which are slim and fairly elegant - no good for economy 7 though as they do instant heat, not saving it. controlled by a nobo orion 700 which controls different zones and times, although in operation it's much simpler than I imagined and if I'd have known I may have gone for simple thermostat/timer

-Steve

-edit-- just found picture in previous post about windows

http://plus.google.com/photos/11426...73633986818?banner=pwa&authkey=COGH55iLiLfuRg

ignore the cable , that was a "temporary bodge" - the permanent outlet is behind the panel

 

[Zebra]

Steve, indeed your panel heaters do look fine. And what do you use to heat water - an electric immersion I suppose?
I am now fairly sure I will put in mains gas central heating, if as Owain says you can have a small system boiler suitable for your central heating load, and then I will heat the water electrically. There will always be the option to install a combi if I change my mind by the time I get around to doing all that!
The idea of running radiators off the woodburner is just too complicated, with nowhere really for all that pump equipment, and no radiators which could operate by gravity as a heat dump, since all the radiators will be in fact lower than the fire which is on a raised hearth, and there will be no radiators upstairs.
So thank you all, I'll leave you to your mystical plumbing musings...

 

[steveb]

yes, electric immersion for water. We also tried and failed to get a sensible solution involving heating water or rads with the wood stove but the logistics were too complicated. I'd probably have fitted a combi if I had mains gas - I would also assume you can use them as a system boiler if in effect you cap off the hot outlet

 

[skier-hughes]

The heat leak radiator cannot dissipate the amount of heat (unless of immense size) likely to be provided by a solid fuel boiler system running at full heat immediately following a power failure.
Unlike gas and oil, where the heating effect can be immediately curtailed, solid fuel takes a considerable time to reduce its heat output hence the need for a large heat dump.

I may be using the wrong terminology regarding a "heat leak" radiator, though I think we're saying the same basic thing, i.e. any solid fuel heating system must be able to safely operate run purely by gravity in case of electricity failure (and thus any pumps in the system).

I don't understand how a hot water cylinder can help perform this function because Sod's Law will ensure that, at some point in time, the power will fail when the cylinder is already full of piping hot water - thus the continued heat from the fire/stove will have nowhere to go.

The only way to dissipate the heat from the fire/stove is to use gravity-fed radiators (and I agree it would likely require more than one). Typically, this will be the entire upstairs CH circuit and, if sized correctly, will be able to dissipate all the heat from a roaring fire/stove when the power fails.

A DHW cylinder may be part of such a system but I can't understand why it's a necessary part - unless it's purely a regulatory issue.

In fact, worms' description seems elegant in its simplicity. A pump could be added for the operation of the downstairs radiators but the system should work safely without power when the upstairs radiator circuit would operate purely by gravity.

Would such a system really not meet current regulations?

We have a valve which is connected to the mains cold water system, so any failure or overheating opens the valve and instead of hot water from the cylinder continuing to go round the boiler we have mains cold water, and another valve opens to allow this cold (now hot) water to dissipate outside.

Once cooled down enough the valves close and normal heating of tank resumes, if it gets too hot again, then valves once again open, so fail safe in event of power failure or overeagerness in heating the fire and tank

 

[Lime]

The heat leak radiator cannot dissipate the amount of heat (unless of immense size) likely to be provided by a solid fuel boiler system running at full heat immediately following a power failure.
Unlike gas and oil, where the heating effect can be immediately curtailed, solid fuel takes a considerable time to reduce its heat output hence the need for a large heat dump.

I may be using the wrong terminology regarding a "heat leak" radiator, though I think we're saying the same basic thing, i.e. any solid fuel heating system must be able to safely operate run purely by gravity in case of electricity failure (and thus any pumps in the system).

I don't understand how a hot water cylinder can help perform this function because Sod's Law will ensure that, at some point in time, the power will fail when the cylinder is already full of piping hot water - thus the continued heat from the fire/stove will have nowhere to go.

The only way to dissipate the heat from the fire/stove is to use gravity-fed radiators (and I agree it would likely require more than one). Typically, this will be the entire upstairs CH circuit and, if sized correctly, will be able to dissipate all the heat from a roaring fire/stove when the power fails.

A DHW cylinder may be part of such a system but I can't understand why it's a necessary part - unless it's purely a regulatory issue.

In fact, worms' description seems elegant in its simplicity. A pump could be added for the operation of the downstairs radiators but the system should work safely without power when the upstairs radiator circuit would operate purely by gravity.

Would such a system really not meet current regulations?

We have a valve which is connected to the mains cold water system, so any failure or overheating opens the valve and instead of hot water from the cylinder continuing to go round the boiler we have mains cold water, and another valve opens to allow this cold (now hot) water to dissipate outside.

Once cooled down enough the valves close and normal heating of tank resumes, if it gets too hot again, then valves once again open, so fail safe in event of power failure or overeagerness in heating the fire and tank

And entirely reliant on the mains water supply not being cut off.

 

[DJH]

That's a new one to me having a valve permanently connected to the incoming mains water supply is surely against the rules. Any such connection used to fill a heating system must have a non return and pressure limiting valve fitted via a flexible pipe which should be disconnected when the system is filled and only reconnected when the system needs charging again after a loss of pressure. As I have said before I'm now out of touch with these things but the requirement for some things do remain the same.

As you describe your safety set up the only thing that would concern me is the thermal shock the appliance will get with cold water circulating in hot heat exchanger especially if it was a cast iron one which I suppose nowadays is highly unlikely.

Doug

 

[DJH]

Talking about safety with over heating appliances I forgot to mention earlier the importance of lagging the entire length of any vent pipes that extend over the top of water storage or heating feed tanks in an unheated roof space. I have, in my time, seen many of these pipes insulated up to the same level as the water in the tanks either because of expense or lack of understanding. The water in a vent pipe will rise and fall according to the temperature of the water below and can, in some instances, be a considerable height above the water level in the tanks and could, in extreme cold freeze, forming a plug inside the pipe. This plug in an overheat situation could lead to pressure building up in the system and the copper water cylinder splitting, or at worst, exploding.

The conditions leading up to this situation could be ideal in that the colder the weather the more chance of frost and the more heat required to keep warm which could lead to over heating...

Doug

 

[skier-hughes]

And entirely reliant on the mains water supply not being cut off.

Of course if we have a power cut and our mains water is turned off we are up the creek, but so will anybody that has gas that let's it blow up their house

 

[skier-hughes]

That's a new one to me having a valve permanently connected to the incoming mains water supply is surely against the rules. Any such connection used to fill a heating system must have a non return and pressure limiting valve fitted via a flexible pipe which should be disconnected when the system is filled and only reconnected when the system needs charging again after a loss of pressure. As I have said before I'm now out of touch with these things but the requirement for some things do remain the same.

As you describe your safety set up the only thing that would concern me is the thermal shock the appliance will get with cold water circulating in hot heat exchanger especially if it was a cast iron one which I suppose nowadays is highly unlikely.

Doug

Maybe my description is a little simplified.

 

[robgil]

We currently have an old one pipe system that doesnt heat the cottage at all, all the rads are way undersized, the boiler isnt strong enough anyway. We have a diverting valve to heat the water through an indirect cylinder that doesnt work properly and the tit who put all this in decided it was a good idea to put the thermostat in an unheated hall way and a vent half way up the wall in the dining room above the only radiator which sucks all the warm air out before it gets a chance to circulate around the room.
We have an unheated stair case with two staircases that also keeps the cottage nice a cool in the winter.

Why did people think this to be satisfactory? we have gone through 2500 litres of oil in the 9 or 10 months that we have been here. Not to mention the numerous cottages I have worked on around the area where builders thought it a good idea to line walls with hardboard, a quick splash of lining paper to hide the ill fitting joints and flat head screws and Bobs your uncle, bish bash bosh instant kindling should the house catch fire. Its a good job they never bothered to put any form of insulating behind the hardboard as this might hinder the flames as the house goes up like a candle.

Were all builders in the last 40 years cowboys?

Sorry guys, rant over.

P.s., have you ever tried to fix a childs stair gate to a hardboard lined wall? I have.