Understanding Your Unvented Hot Water System

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Many of the modern properties in Milton Keynes are fitted with Unvented Hot Water Systems.

 

How to tell if you have an Unvented Hot Water System

Unvented tundish plumbing
Unvented Hot Water System – Tundish

You can tell if you have an unvented hot water system if you have a large (usually white) water cylinder in your property and if you have a tundish (see picture) this indicates that you have an Unvented Hot Water system.

If you have a hot water cylinder but no tundish then it’s likely that you have a vented system which is more common on older properties and is fed by a cold water storage tank in the loft.

 

How your Unvented Hot Water System Works in 3 Simple Steps.

  1. In an Unvented system your hot water is fed directly from the cold mains water supply into the tank.
  2. Once inside the tank the hot water is heated up to temperature either by your central heating system or by an electric immersion heater or a combination of both.
  3. When you turn a hot tap on cold water pushes in through the bottom of the tank and forces hot water out of the top. ( A process called stratification means that the hottest water will always rise up to the top of the tank and the coolest water will fall to the bottom.)

 

Unvented Hot Water System Safety

  • An unvented hot water system stores a large volume of hot water at extremely high temperatures. Hot water at high temperatures and high pressures creates a risk of major hot water leaks or, in extreme cases, explosions.
  • Due to the potential safety risks, your unvented hot water tank comes with a number of safety devices which need checking annually by a G3 Hot Water Qualified Plumber.
    hotwater cylinder explosion
    Hotwater cylinder explosion

     

    The Safety Devices

  • The first safety device on your cylinder is a pressure reducing valve. This limits the water pressure coming into the system in case of surges in the mains water supply.
  • The heaters on your cylinder should also be fitted so that they automatically cut out once a certain temperature is reached.
  • The second safety device is an expansion vessel this is a pocket of air that absorbs excess pressure. It may be inside your cyclinder or you may have a big metal ball external to the cylinder. This is the second line of defence against excess pressure and needs checking and refilling on a regular basis.
  • The next line of defence against excess pressure is the pressure relief valve (PRV) on the incoming water supply. These usually have a red cap and will discharge water into your tundish if the pressure in the pipework gets to high.
  • The last line of defence is the temperature and pressure relief valve (T&P) this also has a red cap and discharges water into the tundish if the temperature or pressure inside the cylinder gets too high.

unvented hot water

 

 

10 Rules When Applying Sanitary Silicon in Bathroom Plumbing

Applying sanitary sealant around baths, showers and toilets sounds in theory like an easy job. Simply squeeze the tube and then smooth it with your finger. Right?

If you’ve ever tried it you’ll know it’s a lot tricker than it first seems and you can quickly get in a mess.

Sealant play’s a really important role in a bathroom. Applied properly it makes a water tight seal, a nice clean finish and also prevents the build up of damp and mould spots.

It’s worth double checking the sealant around your bath and showers as we get a lot of call out to leaks caused by silicon seals that have either been installed incorrectly or started coming away and caused damage to the downstairs ceilings.

 

Ok, so how to do it correctly.

Rule 1: Buy a premium sealant. We always use Dow Corning 785+ Bacteria Resistant Sanitary Silicon.

Rule 2: Buy a set of silicon cutting tools such as Fugi tools.

Rule 3: Use the right colour for the right location. As a general rule white around the edge of baths, basins and showers and clear between the floor and base of the basin and toilet.

Rule 4: Make sure you have a gap for the silicon to take into (i.e. Don’t grout the last row of tiles).

Rule 5: Make sure the gap isn’t too big. Between 3mm and 5mm ideally.

Rule 6: Cut the silicon tube nozzle at an angle using a sharp Stanley knife.

Rule 7: Make sure the area to be siliconed is completely clean and completely dry.

Rule 8: Apply the silicon so that it fires into the gap to be sealed and so that it slightly overfills the gap.

Rule 9: Use the silicon cutting tools to cut (not smooth the silicon). You should be using the sharp side of the tool and cutting away the excess silicon at a 45 degree angle.

Rule 10: Wipe away excess silicon from the tools using a big bucket of trade wipes.

Bonus Rule: Don’t overwork the silicon. Once you have a nice smooth bead with a straight edge leave it alone and don’t touch it any more. Leave the silicon to cure for 24 hrs before testing it.