Conversion from a single loop system

Hi
Looking at your drawing, it won't work piped in like that?

Possibly the rads at he top will work, but the rads at the bottom will not get hot, the pump is pulling the water from the rads, and not the boiler?

Have a chat to a local heating engineer, see if they give you a better drawing?

Regards
Peter

 

No no no it's not that simple I'm afraid

Basically everything is wrong

If you have a one pipe system then rip it out, all of it & the radiators.

 

Theo, as said above...

The Magnaclean should be on the return before the boiler. The pump (circulator) needs to be on the flow before it branches to the two circuits at 'B'.

And I'd imagine that a single 15mm return pipe for the 'bottom' three rads is pushing it.

Other than that, all good . (Unless your boiler needs to have a rad kept as a by-pass (no TRV)?)

But the single biggest issue is as said above - you'd be NUTS to try and re-use any of the existing pipework.

Do yourself a giant favour and replace it all. The rads too unless you are certain they are in good order and thoroughly cleaned out.

You have the basic principle, tho', so you should be able to work this out with the help of Google

A thought - you have drawn two circuits with 3 rads each - does one circuit do the bedrooms, for instance? If so, I'd thoroughly recommend 'zoning' the system by adding 2-port (zone) valves immediately after the flow splits at B. Each will be controlled by a Prog Stat in each zone, so you can have the bedroom ones coming on only in the late eves and early morns, for example.

Pipe sizing - as you say. 22mm main rails to each set of three rads, with 15mm teeing off to each rad as required. When you reach the second rad, use 22/15/15 tees and continue in 15mm for the last two rads (ie you don't need to continue in 22mm until you get to the last rad.)

Once the system is up and running, you'll then need to balance it so that the closer rads don't get the lion's share of the flow.

And, yes, plastic all the way! Soooo much better when doing long runs, especially if it's under the floor - fewer joints. Secure it well, tho', and add lagging even tho' it's already inherently better insulated than copper. Oh, and make sure it ain't a TIGHT fit going through joists and stuff or it'll creak and drive you nuts.

You can clip it to the underside of each joist or - if you prefer - you can drill clearance holes through the centres of the joists.

 

It used to be, with the pumps separate from the boiler (ie not built-in), that they were commonly fitted on the returns because they'd be handling cooler water. But they had to ensure it wouldn't draw in any air from a poorly designed system.

If your current setup has the pump on the flow, then keep it there. It's quite normal. But fit the Magn on the return (cooler).

Is your system vented or unvented?

 

I've gorn boss-eyed.

Magna still in wrong place. I don't think you need balancing valves on each flow, but I'd fit an auto by-pass on the very end of one of the rad runs (or make a bathroom rad un-TRV'd).

But if you don't rip out all the old pipes and redo, we will stop talking to you - you still have single 15mm returns on both sets of rads. (There's little point having 22m flows supplying them if the returns are 15mm.)

Look, man - you are ripping up floors and laying new pipes anyways, so do it all!

 

And if you do decide to go 'zoned', then replace the 3-port valve with a third 2-port fellow. Your main flow pipe - following the pump - will then have three 2-port valves in a row, one for each circuit.

 

Good move, man .

Yes, I should have said - copper tails coming up to each rad. Use a push-fit elbow under the floor to go from plastic to copper.

Get a pro (on here, hopefully...) to confirm that the location of your auto by-pass is ok. I've always seen them on the ends of circuits, but that might be because they were manual ones.

Yes, don't go less than 15mm anywhere. Keep it as planned - 22mm rails going to each set of three rads, teeing down to 2 of 15mm to supply the last two. It doesn't even matter if that last rad is a good few metres beyond the second rad, 15mm will still supply it absolutely fine.

Advantages of zones? Only consider doing this if the three rads on the other section are all doing the same thing, like bedrooms.

If you then have three rads in the 'living' areas and three in bedrooms, each zone will have it's own Prog Room Stat (like a normal wall stat except it also does your timings) and then you set them to give you what you want.

Eg, bedrooms could be 'come ON at 6am at 20oC, then go down to 16oC at 9am and stay there until 9pm when they should go back up to 20oC and then down to 14oC at 11pm...'

Meanwhile, the living areas would be 'go up to 20oC at 7am, down to 16oC at 9am, go back up to 21oC at 5pm and then back down to 14oC at 11pm...'

Once set, it'll do it all for you. The advantages? No one has to run up to the bedrooms in the evening to turn up the rads. The bedroom rads won't come on at all until you actually want them to.

Not essential at all. But, if three rads are bedroom rads, it would be a very good thing to do.

 

Hi
It's a very messy drawing, there are mistakes that will cause you problems if you install it like this.

When I draw a heating diagram, I start with the boiler.

If open vented, the vent and cold feed are draw first,

The primary pipes from the boiler need to form a circuit.

This will include the pump, vent, cold feed and bypass, and filter.

From that, the primary circuit will supply a flow and return to the heating and hot water, only one feed and return to the primary curcuit, for each circuit i.e. heating hot water,

(you have separate returns on the heating side.)

I think I may have started to ramble?

Tips... common heating return required.

Show how the vent and cold feed fitted?

Sermon over!

Regards
Peter

 

Theo, why is the 'top' circuit all in 15mm pipe? It might be ok, but chust seems a bit, y'know...

 

Theo, I agree with DA on going 22mm for all the rails. Then tee off in 15mm legs for the rads.
I used 28mm here but that's a little ott.
You're also right with taking out all the old, take it to the local scrap yard and that will cover a fair bit of the new install. Id also suggest sticking to plastic for the long runs, it saves attempting to solder in tight joints and alkward positions.
Also think you should consider zoning the system. I have zoned my upstairs (including loft conversion) and downstairs separately, so during the day downstairs can be on (keep the misses walm and save me money on bills!) And in the evening upstairs comes on.

DA you covered this well