Can I fit an unvented hot water cylinder in a cellar?

[adrianhar]

Hi
I am about to upgrade my gas boiler & HW cylinder. They are located in a dry cellar, which (because it's below ground level) has no internal drainage facility.

An unvented HW cylinder has been suggested as a replacement. However, I notice that these require a T&P relief valve which must be fitted with a gravity fed outlet through a 'Tundish'. I can't drain off this by gravity in the cellar - it means going uphill!

- Does anyone know if there is a way round this, keeping the same cellar location?
- I appreciate I'll need a condensate removal pump for the boiler as well. Is a similar arrangement feasible (and legal) for the Tundish outlet?

The current system is a traditional indirect vented one, with cold water storage cistern and, boiler feed and expansion cistern in the loft. The roof is a shallow pitch, so I pump both cold and hot water upstairs to achieve a good strong flow to bath, basins and showers. Changing to a new 'System Boiler' is not really a problem.

Perhaps I should just stick to an old fashioned vented cylinder, but the newer ones do seem to be a much higher spec & performance. However, another factor is that the metal skinned ones all have a single 22mm top outlet, and no option for a Surrey/Warix Flange (needed for high flow rate take-off.
- Am I scuppered?

Any ideas would be gratefully received. Thanks.

adrianhar

 

[muggles]

This has been debated many times on here, the general conclusion being that no, you cannot fit an unvented cylinder below the lowest drainage point, as there is no suitable and reliable way of dealing with discharge. The boiler, however, can be fitted down there, provided there is a way of getting the flue out of course! You would need a pressure relief valve that is remote to the boiler, fitted so that it's discharge can run downhill and be visible from outside. There is no requirement to fit a tundish to a boiler.

There is no need for a surrey/waris flange on an unvented cylinder, drawoff flow rate is governed by the incoming mains flow rate, and will be approximately the same as that. You cannot legally pump the mains, so there would be no point fitting a pump to the unvented cylinder to increase flow further.

Before choosing unvented, check that your mains flow rate and pressure is within the specification for the cylinder.

 

[Biggles..]

the answer is obviously yes of course you can and thousands probably are done quite safely and correctly.

you could put all the discharges into a galv tank/sump and then use a sump pump to discharge the waste at a high level,some pumps can be interlocked with the valaves so should the pump fail the cylinder is shut off.

you could just like in every commercial application just discharge onto the floor exactly the same as you could the boiler,the point is the discharge has to be safely located and obviously discharging.Cellar floor is safe and youull deffinately know its discharging.

if your worried about the water on the floor,mount the cylinder on a concrete plinth,gives little bit of flood room.

Lee

 

[Happyplumber]

I totally agree with LCGS,unvented cylinders are fitted in cellars all the time and the discharge taken care of properly

Just a bit of common sense and brains and the discharge can be sorted out properly



Make sure that you speak to a installer who is familiar with the job not a newbie or 6 week course wonder,otherwise you will be lead up the garden path

 

[WDIK]

even straight on to the floor into a sump and sump pump