Whats wrong with this system?

[F1yTrap]

Thank you all so much for your input. I have scrapped the last revision as from your comments there looked to be too many mistakes.

Regarding where the feed/expansion connects to the system, I am somewhat limited on what I can do with it. My only options are to connect it to either the feed or return near the HW tank. To run another pipe back to the boiler room would be a massive job and affect the kitchen and living room, so I'm trying to avoid this if possible. There is not enough room near the tank to introduce the pump.

I have looked at the Honeywell Sundial Plans and revised my planned system to become an S-Type system (I hope). I have taken on board as many of the comments as I can, the only thing that I haven't done is position the vent/feed before the pump. I do however have it entering the system on the feed before the valves. In the event of an overrun and both valves being closed, the system would just vent into the feed tank. If this system is still not correct, maybe it could it be fixed by adding a bypass to the system at some point.

Is this plan OK, legal and safe?

Untitled

• F1yTrap
• 26 Sep 2010
• 1

 

[twgas]

No good I'm afraid. The open vent/cold feed must NOT have any valves in it.

 

[picasso]

Depending on the age and condition of your system and the boiler manufacturers allowing it, you could make it a sealed system, no need to worry about the position of feed and vent etc.

 

[kevplumb]

No good I'm afraid. The open vent/cold feed must NOT have any valves in it.

it hasn't mick unless you mean pump valves

 

[F1yTrap]

God this is hard!

I don't really trust the system enough to support the pressure of a sealed system, think the original fitters were a bit of a cowboy outfit.

My main goal it to convert my existing layout (which back feeds through the HW tank when the CH is on) to a simpler more efficient system. The main constraint is only having three pipes from the boiler room to the bathroom (where the HW tank is).

I tried to base the latest revision on figure 2.7.1 from the link picasso provided http://www.miketheboilerman.com/pipeworklayouts.htm

In 2.7.1 though the vent/feed is on the return, so, in my latest design if I moved my vent/feed to the return after the HW tank, would that do the trick?

 

[picasso]

If you swop the motorised valves for pumps with check valves and take the pump out of the feed and vent, you will have seperate control over heating/hot water and a clear path to expansion tank.

 

[twgas]

No good I'm afraid. The open vent/cold feed must NOT have any valves in it.

it hasn't mick unless you mean pump valves

I do mean pump valves, and any other valve that could possibly be shut, either manually or automatically, as you know (I hope) anything that can block the vent is a no-no.

 

[Axel]

Booooom!

 

[F1yTrap]

There is no where near enough room for a pump near the tank.

I have revised and moved the feed/vent to the return part of the system. I think this now closely resembles figure 2.7.1 "Open Vented System Diagram" does it not?

Untitled

• F1yTrap
• 26 Sep 2010
• 1

vs

Untitled

• F1yTrap
• 26 Sep 2010
• 1

 

[F1yTrap]

I see from my last effort that there could be a problem if both valves are shut, but if I added a bypass just after the pump to the return maybe....

 

[DP]

Look at your private message. Modified drawing sitting on my computer waiting for your email. I am unable to download same onto this post.

 

[F1yTrap]

Hi all, sorry to come back with yet another design but I revisited some of the previous comments and designs and scratched my head a little more to come up with this proposal. Essentially a Y plan, with the pump moved up into the bathroom so the vent/feed can enter the system on the feed before the pump and valve. Will this do the trick? [fingers crossed!]

Untitled

• F1yTrap
• 27 Sep 2010
• 1

Thanks dp for your emailed suggestions I have tried to incorporate your ideas without running a fresh pipe back down to the boiler.

 

[DP]

Do not forget the lockshiel in the HW zone or pump will favour the HW zone when both zones call

 

[F1yTrap]

Ok, I'm going to go with the latest plan and start installation this week end. Before I dive in I have a question, do I need to put anything between the pump and the 3 port valve? A bypass or something in case the valve is closed to both zones and the pump kicks in?

 

[kevplumb]

the pump is wired off the valve

you don't need to the valve always has an open path

but it won't hurt