Whats wrong with this system?

[F1yTrap]

We moved into our house 5 years ago. The heating system was only a couple of years old at the time but there was a problem with the upstairs radiators not getting up to temperature. After some inspection it appeared that the pump had been fitted in the wrong direction. I changed it to the correct way and it fixed the problem and has been fine ever since.

Now I want to change to the mechanical timer controller for a more modern controller. One which I can program a schedule for the heating and water independently. The existing mechanical timer has a 'HW Only' or 'HW & CH' switch, so isn't very economical. I have read that there are a number of configurations/'Plans' that will determine how to wire up the controller.

I have the manual for my (oil fired) boiler and from what I have read the feeds should come out of the top (on either site) and the returns should go into the bottom fittings. One side for the HW and one side for the CH. However, from what I can make out my system looks completely wrong. I think the pump may be on the wrong pipe. Also the feed/vent tank feeds back in to the vent pipe, is this correct? My biggest concern though is that it appears that the return for the upstairs radiators is back down the HW feed. It doesn't look feasible but I am 95% sure this is how its set up.

I have made a diagram of my current system. I would really appreciate some feed back on what 'Plan' mine is. Also what would I need to do to make it adhere to a more efficient Plan.

Here is the setup:

Heating Setup

• F1yTrap
• 25 Sep 2010
• 2

alternativly the image can be accessed via: https://docs.google.com/drawings/edit?id=1Oz-x2xHHkvlhp9ga0ruYGOC5OibOhfu25KXyrByPVV8&hl=en

Thanks in advance for any help.

 

[kevplumb]

pump is pumping the wrong way

 

[F1yTrap]

Thanks kevplumb, but when the pump was on the other way (as it was when we first moved in) the upstairs radiators didnt get hot enough.

 

[kevplumb]

move the pump to the flow at or near to the boiler and move the tee to the flow side

upstairs rads on your dwg are sharing the flow with the cylinder
they can share the return not the flow

 

[picasso]

This is what your system should look like

http://www.miketheboilerman.com/pipeworklayouts.htm

if you want more control you could fit a 2 port valve in the return of the cylinder (c plan ) or convert it to fully pumped (s plan).

http://www.heating-and-plumbing-solutions.com/AddCont.pdf

 

[F1yTrap]

Thanks picasso and kevplumb for your fast replies. I have taken on board what you have both said and revised my drawing to what I think will conform to a Y-Plan system. Is this setup correct?

Untitled

• F1yTrap
• 26 Sep 2010
• 1

 

[Agile]

It would work but its not correct!

The combined vent and feed should be directly connected to a boiler flow connection. Safety issue!

I appreciate that it may be difficult to change it but reversing the flow on the upstairs rads is only likely to be possible without problems as long as you dont have any TRVs.

Tony

 

[F1yTrap]

Thanks Agile - If I swap the vent/feed back to the Feed (as it currently is, and is in the first diagram) would that overcome the "Safety Issue"?.

No TRV's on upstairs Rads. I will put some on once I have the flow working correctly!

 

[kevplumb]

The combined vent and feed should be directly connected to a boiler flow connection. Safety issue!

yeah yeah

move the feed/vent to before the 3 port valve

as long as the feed/vent has a permanently open path it will be fine

 

[picasso]

Thanks Agile - If I swap the vent/feed back to the Feed (as it currently is, and is in the first diagram) would that overcome the "Safety Issue"?.

no you need to move the combined feed and vent between the boiler and pump.

 

[DP]

Picasso, in your link, figure 2.7.1, there is no pump. Also, should the combined feed and vent not be connected to flow pipe before the'missing' pump?

 

[picasso]

Hi dp, I didint look at the diagram below the semi gravity system I was pointing the op to, the boiler in the diagram 2.7.1 has an integral pump although I have never seen an open vented system (as recommended by keston) done like this.

 

[onlyfitidealboilers]

fit the three port & pump next to the cylinder, then fit the cold feed open vent before the pump??

 

[DP]

You got me there Picasso.

 

[twgas]

looks likely to suffer from reverse circulation as well.
Rad returns should all join together before joining with the HW return then back to boiler, or seperate returns for HW and CH going right back to boiler.