Flow- Vent- Feed -Pump

[desktop987456]

I thought, I'll start a new thread for clarification. Does this look right? If I have understood it clearly, it is a flow loop from boiler to rads?

 

[Madrab]

Yup ... open vent system

 

[desktop987456]

I have selected this loation for new boiler on first floor. Gas connection, condensate drain, feed pipe (serving as common vent as well).

My previous boiler was on ground floor just below this location and had a pump inside boiler, in 2nd photo you can see pipes going downstairs to rads.

I am slightly careful about where to place the pump and based on VCP principle, would I be alright in terms of pump location (after vent), marked on 2nd photo? I understand that I have to raise the feed tank above the boiler but other than does this look correct for installation. This is not in UK so UK laws don't apply here but will try to learn and follow best practices used in industry for OV system.

 

[Madrab]

It's not about UK laws. it's about the laws of physics. The connection setup you have in pic 1 is the ideal to ensure proper circulation, venting and feed. Any other orientation will alter the system pressure characteristics and could cause problems.

The pump needs to be placed after the feed and vent with the flow away from them to keep the system under positive pressure. The boiler can really be fitted anywhere in the chain, if it's a HO but there are more favourable positions for it, depending on the system layout. The vent also needs to be a certain height above the F&E cistern to avoid pumping over and the cistern needs to be the highest point on the system.

Can I advise that you do a fair bit of extra research if you a looking to plan and fit an open vent CH system, lots of OV design stuff available online. It is level 3 stuff for an experience professional but not so much for a novice DIY'er. The basic design principles and the standards that must be applied, needs to be know and understood to ensure the systems works properly. Of course, it isn't beyond a competent DIYer but getting tips on a DIY forum wouldn't be the recommended way to do it IMO

 

[desktop987456]

It's not about UK laws. it's about the laws of physics.

I couldn't agree more but I thought I clarify this upfront based on my previous posts where I few members pointed that this is a UK forum so UK regulations apply in the forum.
I have read a couple of books to get understanding of heating systems and I am on my learning curve, done heat loss calculation and optimized my CH system. Recent hike in energy prices have forced me to change to a condensing boiler. My old boiler was 60% efficient hence these questions as I need to do it right. I will not be doing the work by myself and will hire someone to do it but heat engineering and efficiency is non existent in this part of the world. I couldn't get a boiler for my designed load? The minimum boiler here starts from 24kw! I bought a 13kw boiler (for Central heating only) from UK.

 

[fixitflav]

I thought, I'll start a new thread for clarification. Does this look right? If I have understood it clearly, it is a flow loop from boiler to rads?

That's OK, but don't forget up and under for the cold feed. Also the vent and feed should be maximum 150mm apart, as you've possibly seen if you've been reading up on it.

 

[desktop987456]

That's OK, but don't forget up and under for the cold feed. Also the vent and feed should be maximum 150mm apart, as you've possibly seen if you've been reading up on it.

Thanks. I have got a pre plumbed pump and motorized valve that came with the boiler. I have marked the picture with arrows for clarity. What this small screw with a vent for (bottom left on pic) ?

Secondly, Do I have the connections right from boiler and into the flow pipe? Thanks

 

[fixitflav]

What this small screw with a vent for (bottom left on pic) ?

Looks like a vent but it won't do much venting in that position, but it probably isn't essential. Is it possible to rotate the pipe so it's upwards, or would the vent screw then hit the wall?

Secondly, Do I have the connections right from boiler and into the flow pipe?

Yes, assuming it's pumping from right to left, which it should be if it's a pre-plumbed arrangement

 

[Harry Bloomfield]

I thought, I'll start a new thread for clarification. Does this look right? If I have understood it clearly, it is a flow loop from boiler to rads?

Simple way to confirm...

With pipes and boiler cold, fire up the heating and feel the pipes to see which gets warm first.

 

[desktop987456]

It hasn't been fixed yet, I was just holding it this way to ascertain correct orientation.

Is it possible to rotate the pipe so it's upwards, or would the vent screw then hit the wall?

you mean the whole thing so pump is facing upward direction?

 

[Madrab]

That's a 3 port valve, so you would be setting the system up as a Y plan with Ch and a Hot water cylinder. It will need a motorised head that would be controlled through what called an interlock, so a couple of thermostats and a programmer. Not the best TBH so be prepared to swap out the 3 port motorised valves during it's life. It would be better as an S plan with 2x2 port valves. Feed and vent would be piped in before the pump even then though, is setting it up as a sealed system not possible?

As the 3 port valve sits then it's AB = the inlet from the pump. A = the outlet to the Rads, B = the outlet to the Hot Water cylinder, forget about the air vent that's on it, it's kinda pointless where it is, either cut it off and cap or just leave it locked off and never touch it.

 

[fixitflav]

It hasn't been fixed yet, I was just holding it this way to ascertain correct orientation.

you mean the whole thing so pump is facing upward direction?

No, I meant just the bits after the 3-port valve. Looking at the top of the T, towards the 3-port, rotate it 180°

 

[desktop987456]

Ah ok.

 

[desktop987456]

That's a 3 port valve, so you would be setting the system up as a Y plan with Ch and a Hot water cylinder. It will need a motorised head that would be controlled through what called an interlock, so a couple of thermostats and a programmer. Not the best TBH so be prepared to swap out the 3 port motorised valves during it's life. It would be better as an S plan with 2x2 port valves. Feed and vent would be piped in before the pump even then though, is setting it up as a sealed system not possible?

As the 3 port valve sits then it's AB = the inlet from the pump. A = the outlet to the Rads, B = the outlet to the Hot Water cylinder, forget about the air vent that's on it, it's kinda pointless where it is, either cut it off and cap or just leave it locked off and never touch it.

The motorised valve, filter, pump came with the boiler (Viessmann 100-w heat only wb1b). I intend to install it for central heating system only as I have direct source for water heating. If this is installed correctly I intend to get an indirect cylinder (with coil and immersion element) and install it as you say via Y or S plan system in future. If I leave the motorized valve as it is and leave it at central heating it should work fine for central heating?

I am skeptical going for a sealed system (based on my limited knowledge) but I keep reading the debate about sealed vs OV system due to maintenance involved. Are there any benefits in running it as a sealed system, I need to install an expansion vessel for conversion, Correct?

 

[fixitflav]

If I leave the motorized valve as it is and leave it at central heating it should work fine for central heating?

Yes. Obviously you need to blank off the pipe going to the future HW cylinder.

I am skeptical going for a sealed system (based on my limited knowledge) but I keep reading the debate about sealed vs OV system due to maintenance involved. Are there any benefits in running it as a sealed system, I need to install an expansion vessel for conversion, Correct?

Personally I prefer open vented, but if starting from scratch there probably isn't much in it costwise.
Each has its pros and cons, as you've been reading about. I'm a DIYer, but I believe opinion in the trade is divided.