Trianco Tro 50/73 tappings

[Chapster]

hi everyone,

At work the above boiler is fitted supplying office heating and an immersion. It's on a Honeywell controller and hasn't been connected properly because turning off the hot water on the controller disables heating to half the building too.

I'm the electrician at my workplace and have been asked to see if it's been wired up wrongly but first I need to understand what's going on. The boiler has six tappings, three each side: top, middle and bottom, 5 of which are used, one bottom tapping blanked.

The radiators in the office aren't flow and return but have single pipe with both ends of the rads connected to same pipe. What I'm finding odd is there are two external pumps fitted around the boiler which seem to be fitted: one between top and diagonally opposite bottom tapping. One between middle and bottom tapping with isolation valve fitted which presumably allows it to draw from system instead of pumping in a tiny loop.

Why are there 6 tappings? Why a pump between tappings instead of inline with flow?

Thanks for any help

 

[Chapster]

 

[Terrywookfit]

I have never seen a TRO with 6 tappings. The norm is 4 x 11/2" top and bottom Left and Right and an 11/4" tapping on front to enable pump to be fitted in the casing.

The pump across top and bottom diagonals could be a shunt to prevent "Back end rot".

Photo's would be good!

 

[Chapster]

I was a bit of a muppet... it has four tappings. The middle two are actually a continuous pipe running behind the boiler, but as it's so close to a wall I couldn't tell at first.

So in my drawing, the middle is a pipe running behind boiler, so three return pipes going to manifold.

What's back end rot, out of interest?

Not in work now but can take a photo tomorrow, although it's as per drawing but no middle tappings.

Seems configured so immersion is only heated when central heating is on, as there's no separate dhw pump and no diverter valve.

 

[Terrywookfit]

Without motorised valves and controls it is not possible to have independent control of water and heating.
You will probably find that the water channel switches the boiler on/off and the heating switches the pump.
The water could be gravity circulation and possibly some of the rads.

 

[Chapster]

Thanks Terry, you were spot on with the above post. Workplace happy to leave it as is, so my job is done. Thanks again.