UFH Buffer Tank Query

bauderline

Due to lack of interest in the C&P forum I am asking this question again here as I know a few plumbers trawl this forum...

I have built a circa 6000 sq ft house and I am installing a 200,000 BTU Grant Vortex oil boiler. The entire house has UFH and MVHR and is very well insulated.

What size of buffer tank should I install to get good efficiency from the oil boiler ? I am thinking either 1000L or 1500L should be sufficient as I am not depending on a single flat out burner you would get from a log gasification boiler...

Any thoughts folks ?

Best regards, Peter.

bauderline

.. still angling for some help with this ? Anyone any thoughts at all ?

P.

PeteHeat

Hi,

I expect you know that most buffers are fitted with wood pellet or wood gasifiers as the primary heat source, so most people size the buffer to suit the boiler.

If you had a 200,000 btu wood burner you would need a buffer of approx 3000 litres depending on the boiler.

As you will be using the buffer to prevent the boiler from cycling while still providing your underfloor with heat on demand / when requested by each room thermostat which I believe is the best way to run UFH.

I expect 1,000 litres should be enough however it is best to check with your plumber / system provider as the flow and return temperatures do have a bearing on the amount of heat required.

I hope the above is of some help.

.

bauderline

Pete,

Thanks for your input.... I was thinking of installing a wood gasification boiler into the system at a later date... I might be better to install 3000L of thermal store now, however I am worried that I might end up with a lot of unused heat if you know what I mean.

Also is there any problems using 2 x 1500L tanks for a 3000L thermal store ?

... one last thing that is not clear to me.. how do you configure the boiler to fire and charge the buffer tank ? Should it be set to automatically fire anytime the temp in the cylinder drops below a certain level rather than being on a timeclock ?

Best regards, P.

PeteHeat

Hi,

Without knowing a lot more about your heating system I can only give a guide answer.

The first thing I would do is have the heat calculations carried out for your house it is possible that you have over sized the boiler, nothing worse than compounding one mistake with another by installing an over sized wood gasifier.

Assuming everything is sized properly there should be no problem linking the buffer stores at a later date.

The most important item to consider is the size needed for the plant room as good quality heat stores take up a lot of space and the room should be well insulated to prevent heat loss from the tanks.

We would use a temperature differential controller to fire the boiler based on the temperature of the buffer store, if you follow the idea that the boiler is responsible for heating the thermal store and not the house it gets easier.

So when a room or rooms call for heat the buffer serves that request, only when the temperature in the buffer falls low enough (example 50c) should the boiler need to fire up.

The boiler is then able to run at full output, which is the most efficient for most good quality boilers, it has the benefit of a warm return temperature from the buffer which also improves efficiency.

I hope the above is some help.

.

Handy100

hello peter..just wondering if you got someone to do the retaining wall 6m long for you . would appreciate a call back to discuss . my no is 086 0863704.. regards ..pat..