Pressurised buffer tank with solid fuel

froshtyv

Hi,

I have looked a previous threads on here and i'm wondering if anyone can point me to the regulation on this or give any input.

Basically a solid fuel stove is to be connected to a pressurised buffer tank which is feeding the heating system.

Some plumbers say not to pressurise the buffer tank at all and leave it open vented.This means installing a heat exchanger between the heating circuit and the buffer tank.

If the buffer tank is to be pressurised then at a time of a power cut with the solid fuel stove being lit, that the energy produced by the stove needs to be directed away from the pressurised buffer tank by means of a gravity fed heat dump rad. This is done by means of a normally open 3 port valve.

By installing a 3 port valve on the solid fuel circuit does this contradict on what some people about not having any motorised valves etc on this line?

Even though with a normally open 3 port valve it diverts to the dump rad when there is no power.

Any input on the above would be much appreciated.

With unvented cylinders (which a lot of buffer tanks tend to be) you cannot use a 3 port, must be a spring return two port wired to a stat on the buffer, you cannot use a solid fuel stove direct(uncontrollably heat source).

For any clarification look to the manufactures instructions for the buffer tank as they must be adhered to.

Pressurised cylinders rarely get the respect they deserve commonly they cause thousands of € worth of water damage due to installers not reading the instructions and if fitted really badly then after the kaboom unvented cylinders can make a home look like a loose brick covered carpark.

Go with the plumbers that want to fit a plate heat exchanger.

froshtyv

gary71 wrote: »

With unvented cylinders (which a lot of buffer tanks tend to be) you cannot use a 3 port, must be a spring return two port wired to a stat on the buffer, you cannot use a solid fuel stove direct(uncontrollably heat source).

For any clarification look to the manufactures instructions for the buffer tank as they must be adhered to.

Pressurised cylinders rarely get the respect they deserve commonly they cause thousands of € worth of water damage due to installers not reading the instructions and if fitted really badly then after the kaboom unvented cylinders can make a home look like a loose brick covered carpark.

Go with the plumbers that want to fit a plate heat exchanger.

Thanks for the reply. The 3 port that would have been proposed to be used would be a spring return also. I dont see the difference between using this and a 2 port normally open valve?
The reason i wouldn't like the 2 port valve is due restrictions i have seen on the internal valve. So a DN25 valve may not have a full DN25 bore thus putting a restriction in the pipe work.

The stat would be put on the pipe work leaving the stove. It would be set a circa 30°C. When this is reached the 3 port valve would divert from the dump radiator and go to the buffer tank.

If power was to fail with the solid fuel still lit, the 3 port would spring return to the sump rad thus stop heating the buffer tank.

froshtyv

froshtyv wrote: »

Thanks for the reply. The 3 port that would have been proposed to be used would be a spring return also. I dont see the difference between using this and a 2 port normally open valve?
The reason i wouldn't like the 2 port valve is due restrictions i have seen on the internal valve. So a DN25 valve may not have a full DN25 bore thus putting a restriction in the pipe work.

The stat would be put on the pipe work leaving the stove. It would be set a circa 30°C. When this is reached the 3 port valve would divert from the dump radiator and go to the buffer tank.

If power was to fail with the solid fuel still lit, the 3 port would spring return to the sump rad thus stop heating the buffer tank.

You cannot fit a 3port valve to a unvented cylinder this is due to 3ports failing in the past, so for safety sake do not fit one.

froshtyv

gary71 wrote: »

You cannot fit a 3port valve to a unvented cylinder this is due to 3ports failing in the past, so for safety sake do not fit one.

Is it not the same for a 2 port valve failing though?

I cant see the difference if both were to fail why you would use one over the other?

Dtp1979

froshtyv wrote: »

Is it not the same for a 2 port valve failing though?

I cant see the difference if both were to fail why you would use one over the other?

You can fit a 2 port no problem, as long as you don't have a solid fuel appliance as the fuel source

froshtyv

froshtyv wrote: »

Is it not the same for a 2 port valve failing though?

I cant see the difference if both were to fail why you would use one over the other?

I'v seen thousands of installations and have seen the damage caused when 3ports fail, never had a two port fail.

You asked for regulations i'v given them to you(as far as unvented cylinders are concerned) as for the difference if you fit a 3 port you are liable in the event of a insurance claim, if you fit a two port you are not unless you're using a uncontrollable heat source.

Have a look at your tanks instructions usually they point to UK water regs/G3 which are enforced in Ireland by the insurance companys.