unvented water cyclinder discharge

[toadhall]

Hi, I am upgrading my water cylinder to an unvented system. My cylinder is in the basement so I am looking at getting some sort of sump pump to allow for drainage from the cylinder.

Can anyone tell me how much water discharge I can expect from an unvented cyclinder? My impression is that if they go wrong, they release water as a safety feature, but most of the time they should be dry.

Is this the case?

Cheers

 

[Fluffster]

You are correct most of the time they should be dry. If a relief valve operates at full flow you may have very hot water at 3 bar plus released so you need an appropriate discharge network in place. You should check with the manufacturer if they advise on a sump pump. Most sump pumps cannot run water over 35 degrees from the top of my head. The D1/2 Pipes are covered by building regs and state a continous fall etc however mnaufacturer instructions take precedent so if they advise upon a pump go for it.

Pete

 

[Onetap]

Yes.

If the expansion vessel or air bubble loses some air, it could discharge several litres of water every time it heats up; this will probably happen at some time during the life of the heater.

If one of the relief valves fail, it can discharge water continuously at mains pressure. Although this shouldn't happen, it is quite possible that it could happen over the 10 or 15 year life of the system. You could come home to find you've acquired an indoor swimming pool.

If the immersion heater thermostat fails 'ON', the T&PR valve will discharge several litres of very hot water at mains pressure every few minutes. The incoming cold water serves as a safety feature, cooling the cylinder; a water cut-off device alone would create more hazards.

 

[toadhall]

thanks guys.

I actually have an empty storage tank in the basement floor (no idea why!) which will fit 400+ litres so was think of letting the cylinder drain into that until i can think of a way of pumping it out.

toby

 

[RickMoore]

You do have your Unvented Hot Water certificates I take it ?

Building regs very clearly state the allowable D1 and D2 dishcharge arrangments and I can't recall seing termination to an unused tank to be in there.

Do you realise the consequences of incorrectly fitting an unvented cylinder ?.

http://www.youtube.com/watch?v=9bU-I2ZiML0

 

[McCombi]

You do have your Unvented Hot Water certificates I take it ?

Building regs very clearly state the allowable D1 and D2 dishcharge arrangments and I can't recall seing termination to an unused tank to be in there.

Do you realise the consequences of incorrectly fitting an unvented cylinder ?.

http://www.youtube.com/watch?v=9bU-I2ZiML0[/QUOTE]


Dont think the op stated he (i assume) was going to do the install himself.

Most state that the discharge pipework has to have a fall and terminate in safe and visible location.

 

[RickMoore]

Dont think the op stated he (i assume) was going to do the install himself.

Possibly, My thought was that a professional installer would have already addressed these concerns, as they are kind of critical to the viability to the job. Perhaps the OP meant to start his post "I am thinking of upgrading to an unvented cylinder" ?

I can't see an old water storage tank fitting the description in ADG 3.61 of terminating in a safe place

 

[toadhall]

Hold your horses.
I'm not touching the the installation. Have had several people look at it and all are happy with the discharge going into a tank with a suitable pump in the tank taking the water to the drain.

My question was to assess what the tech spec of the pump is that will be fitted in the discharge tank - i.e. capable of pumping hot water at mains pressure.

 

[toadhall]

Just had a a plumber look at the problem and he has suggested a thermal store cylinder to get round the problem of having to set up drainage and still provide mains pressured hot water.

Do they work?

 

[mickyg]

Just had a a plumber look at the problem and he has suggested a thermal store cylinder to get round the problem of having to set up drainage and still provide mains pressured hot water.

Do they work?

yes they work fine but they do have their downfalls depending on how they are designed.

try these guys for a sump and pump, won't be cheap though

http://www.pumphousepumps.com/

 

[toadhall]

yes they work fine but they do have their downfalls depending on how they are designed.

thanks. I'll check out these pumps. Do you know where I can read a review of the pro/cons of these thermal stores?

 

[mickyg]

well i can tell you what to look for in a thermal store...make sure the heating circuit is from a dedicated coil in the tank and make sure the store doesn't include any of its own sensors or pcbs. also make sure its stainless steel not copper, but plenty of info about if you search

 

[Onetap]

yes they work fine but they do have their downfalls depending on how they are designed.

thanks. I'll check out these pumps. Do you know where I can read a review of the pro/cons of these thermal stores?

Search the archives on here.

I wouldn't go along that route; they're carp.

They were the only means of getting high pressure hot water before unvented hot water storage systems were permitted in the UK.

You need to keep the store at a high temperature to generate hot water at an adquate flow rate. In London, you'll get a lot of limescale deposits from overheating the water (before blending it with the TMV on the outlet). They are affectionately referred to as 'sludge buckets'. They also require an open vented heating system.

PS You also need to have the mains flow rate and pressure checked before installing a unvented cylinder. Most of London's water supply was installed with 1/2" service pipes, which is adequate for a storage tank, but inadequate for mains pressure systems.

 

[toadhall]

Thanks. This seems the general consensus that thermo stores don't work especially in london (which I am).

My options for a basement system.
1. Thermostore, sludge problem bad pressure, scalding taps, breakdown
2. Unvented plus expensive sump pump, bad pressure, high maintenance costs
3. Gravity fed sytem with noisy shower pumps that don't last more than a year, tank in loft

Crikey, I live in an terraced house in london, similar to 5m other people. I can't believe these are my options. What a shower of preverbial.

 

[Onetap]

Thanks. This seems the general consensus that thermo stores don't work especially in london (which I am).

My options for a basement system.
1. Thermostore, sludge problem bad pressure, scalding taps, breakdown
2. Unvented plus expensive sump pump, bad pressure, high maintenance costs
3. Gravity fed sytem with noisy shower pumps that don't last more than a year, tank in loft

Crikey, I live in an terraced house in london, similar to 5m other people. I can't believe these are my options. What a shower of preverbial.

4) Electric shower.
5) Combi boiler
6) Mains pressure, non-storage instantaneous system with a plate heat exchanger, as installed in a combi boiler, but using a separate boiler.

See this Jimmy, done by someone who posts here;

http://youtu.be/Ft5fsHQy-Wg

It has advantages and disadvantages, if you can find someone who could install such a thing.

The mains pressure is only an advantage for showers, most other outlets are adequate with a supply from a storage cistern if you have loft space.