MikeGrahamT21

Central Heating Manifold system

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Hi,

 

I'm planning on re plumbing all of our radiators, with brand new insulated pipework (currently uninsulated) as I re-do the floor in each room. At present something is definitely not right, as the return temperature on the boiler is almost the same as the flow temp, so figure starting from scratch is likely the best option.

 

Because of this stage by stage process, I was thinking of using an Emmeti T1 (if I remember right) manifold installed under the floor in the hall, with brand new 22mm flow and return back to the boiler (tee off the existing pipes) and then 10mm back to the radiators using plastic plumbing so I can do continuous runs with no joints to each room, with the only joints being at the manifold, boiler and rad. Would get either push fit TRVs (if i can find them at a decent price), or the push fit adapters if not. Does this sound sensible?

 

Radiator in the main living room will be our bypass, with no TRV. Is this right? Do we need any other form of bypass in case for whatever reason someone does turn both lockshields off?

 

Would radiators in this scenario need balancing, or not so much since the pipe run to each will be almost identical in length. Currently we get around 10C drop on the rads, despite the boiler return temp being pretty much the same (think there must be a bypass somewhere, which shouldn't be there).

 

We have 5 radiators, and 1 towel heater with no plans for wet underfloor heating in the future, boiler is a condensing with built in pump. Is 10mm to the rads sufficient, or would 15mm be better?

 

Also with regards radiators, which type are the most efficient, traditional or flat panel? Can you still buy aluminium?? or mild steel ones? Am I right in thinking it would have to be either ally or steel, seem to remember something from GCSE science about a reaction if you mix 2 types in one system.

 

Thanks for any input.

 

Regards

Mike

Edited by MikeGrahamT21

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Whilst on the subject of heating, I'm specifying a radiator for our new extension which we hope to knock through into next year, which has a vaulted ceiling, only 3m x 3.3m. I've tapped all the u-values and dimensions into the BRE Heating Load calculator which has come out with a design heat loss of 353W, and recommends an emitter of 567W minimum. I'm not too sure just how much to believe this, and was going to go overkill on the radiator (nearly 3000W), would this cause any issues bar costing my more money up front? Presuming with a TRV it would turn off anyway once it got to temp.

 

Boiler is a 24kw, but system is only small, and thought a large radiator may give me more scope for dropping the return temperature to allow the boiler to condense, or would this hinder, since it would be turned off via the TRV quicker than a smaller rad? Given the max BTU and W output on the boiler, this included in our system won't be anywhere near it.

 

This one is a double radiator (vertical column), if you think its really too big, I could drop back to a single radiator, obviously half the output.

 

Regards

Mike

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On 13/10/2017 at 16:38, MikeGrahamT21 said:

Radiator in the main living room will be our bypass, with no TRV. Is this right? Do we need any other form of bypass in case for whatever reason someone does turn both lockshields off?

Hi mike. 

The bypass rad needs to be the one that shares the same space as your room thermostat, so usually the hallway where you don't need to have a TRV / individual room control. 

The return temp won't be lowered unless any rad has dissipated the heat into the room, so a big rad will need to dissipate a lot of heat. I'd go for smaller rads run hotter to get into the condensing range whilst not overheating the rooms. ;)

By al means fit a bigger rad in the extension if you want as you can't turn a small rad up, but you can turn a big rad down. 

As far as a full manifold is concerned it's a bit overkill TBH, plus you wouldn't really want it under the floor. Just use these and these ( random ones off internet grab just for eg ) and cap off each outlet with a bit of pipe and a cap end, which you remove and discard every time you add another rad ?

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Yeah I did see those smaller cheap manifolds. Any reason why you wouldn't want it under the floor? It would be accessible at all times via an access panel in the floor.

 

I've scaled the rad back in the extension from a double to a single, giving around 5000 BTU, still 3 times the requirement suggested by the BRE tool.

 

Living Room Radiator (bypass) is where the stat is located so that should be spot on.

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Also what about the magnetic filters on the 22mm pipes? I saw some yesterday which allow the filters to be taken off for replacement without draining the system which seemed a good idea, it suggested one for flow and one for return which seemed a bit OTT, would a single one on the return suffice? Or would you not bother at all?

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Just now, MikeGrahamT21 said:

Also what about the magnetic filters on the 22mm pipes? I saw some yesterday which allow the filters to be taken off for replacement without draining the system which seemed a good idea, it suggested one for flow and one for return which seemed a bit OTT, would a single one on the return suffice? Or would you not bother at all?

 

I think you now need them for Part L

 

Cheapest ones are from BES - and they are pretty good. Intaklean brand ones and are well made

 

https://www.bes.co.uk/intaklean-2-magnetic-filter-22mm-22807

 

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2 minutes ago, PeterW said:

 

I think you now need them for Part L

 

Cheapest ones are from BES - and they are pretty good. Intaklean brand ones and are well made

 

https://www.bes.co.uk/intaklean-2-magnetic-filter-22mm-22807

 

Couldn't remember the Part letter, this one is cheaper than the one i saw yesterday, looks good and also pretty much the same as the one i saw. Would you use two, or just one on the return so the boiler doesn't fill with rubbish?

 

Edited by MikeGrahamT21

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Only needs one - in the return next to the boiler

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Finally got round to measuring all my pipe lengths, need around 100m in 15mm and 25m in 22mm.

 

I'd got everything decided what I was going to get, a disman 8 port manifold, with tectite MLCP Pex-Al-Pex pipe, but my word is it expensive! Looking around £300 just for the pipe alone.

 

My other option is Pipeplus, which has an EVOH oxygen barrier, and is far superior in terms of oxygen penetration compared with the likes of the JG barrier pipe, and is a much better £61 + VAT per 100m, also in the standard 15 and 22mm sizes.

 

The tectite is clearly better overall, but would you spend the extra on it? This is just for wall hung rads, not underfloor heating. If 16mm TRV's existed, it wouldn't be an issue, i'd just go straight for the european 16mm MLCP Pex-Al-Pex pipe, which is very cheap, but I can't seem to find any.

 

I'll try looking for radiator stems with 16mm push fit or compression ends

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My other concern over the MLCP, it all seems to mention press-fit, which seems a step backwards from pushfit?

 

The tectite is push fit, so it seems the euro stuff is the press fit.

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What's the reason for not using a pretty standard set up of Hep2O and, if needed, their manifolds...? That would mean its all out of the box components that have no real compatibility issues, and if you want to have a "nice look" then you can transfer to copper for the last 250mm to the valve.

 

If you really want a stainless manifold, the Emmetti ones can be supplied with 15mm cones.

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Yeah i've looked at several solutions.

 

The MLCP appeals due to its strength and bending radius, plus there is the chance of mice under the floors here (it has happened before). Emmetti manifolds are nice, but once you have all the bits, very expensive. The oxygen barrier too, isn't really suitable for CH with JG and the like, and most only work to around 50C, which is below where the CH would be. Happy with the plastic look, my idea was to bring both pipes up in the centre of the radiator, up behind the rad, and bend them back down to tails off of the valves, and finally box the pipes coming from the floor to create a robust install which can't be caught by things such as hoovers.

 

Maybe I'm going a little OTT?

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You can buy these which go onto the end of the 16mm pipe and straight onto a regular rad valve. They are rated to go directly into a compression 15mm bend / elbow but would do this task just as easily. 

Most trvs have a very short pipe entry, and they may not be compatible, so best to buy one of everything, those adaptirs, a TRV, and a locksheild valve and make it up to see if all's well. 

You could PTFE these onto regular angled rad valves and then fit the adaptors onto that to take the pex back horizontally but then will you be able to form a bend to drop vertically ? 

You could drop a fitting by using these and take the 16mm + adaptor straight to the valve horizontally. Bit pricey though. 

The last time I did this I did as @PeterW suggests and ran short, neat bits of 15mm copper, bent ( double sets ) back to the skirting boards and converted under the floor at each valve. 

If your using room stats to control actuators on the manifold, then DO NOT fit trvs. ;)

 

Edit : nowt wrong with dropping to a 15mm manifold and 15mm Hepworth pipe ;) 

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I'd originally seen these to allow the PEX to be horizontal: https://www.plumbnation.co.uk/site/towelrads-15-15mm-pushfit-chrome-elbow/?gclid=Cj0KCQiArYDQBRDoARIsAMR8s_QfgrEpNY7eCR34kmQfaPVRGg4VrQvs3IldRN9lx-_f0OcSlDVMeIsaAu-yEALw_wcB

 

No good for the 16mm like, i'd have to get a converter, or use the bend you suggested above and an adapter, which would be cheaper overall. Yeah not using actuators, as I plan to get Tado Smart Radiator TRVs at some point when they come down in price a bit.

 

The Central entry point for the pipes is for a number of reasons, firstly so I only have to cut one hole in the floor, and secondly so I don't really have to worry about radiator sizes in the future and the pipes then being in the wrong place.

 

PSW Trade Suppliers have a number of very well priced products, I've sent them an email regarding their manifold just to see what it actually comes with, but I've made a list of everything i will need for a 16mm pipe system, with manifold, which comes in at £440 for 7 radiators, which i didn't think was too bad. 

 

Actually thinking about it, instead of using the elbow, building on your suggestion, how about these? https://www.pswtradesuppliers.co.uk/en/products.php?product=Female-Elbow-16mm-%2d-1{47}2''-%2d-COMPRESSION-Fit. Not sure what size is on the end of a TRV, they do both 3/4 and 1/2, yours is half hence why i linked this one. That would get me a pretty native 16mm connection in the direction i want off of the TRV and lockshield

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if you went with Stelrad Vita Eco rads their fittings are in the middle and take Eurocones IIRC.

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2 hours ago, MikeGrahamT21 said:

a 16mm pipe system, with manifold, which comes in at £440 for 7 radiators

Breakdown please? ?

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14 hours ago, dpmiller said:

if you went with Stelrad Vita Eco rads their fittings are in the middle and take Eurocones IIRC.

Yeah I looked at those, but for any decent size you have to get a double with 2 convectors, and they hang off of the wall quite a bit, plus they are very expensive! Seem a good idea overall though, pumping less heat into the walls.

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Component Quantity Price Shop
Underfloor heating manifold 8 PORT 1 114.2 PSW Trade Suppliers
16mm PE-RT/AL/PE-RT 100m 1 40 PSW Trade Suppliers
Pipeplus 22mm x 25m Grey Barrier Pipe 1 24.45 Plumbling and Heating Solutions
Climaflex Pipe Insulation - 22mm x 19mm Wall x 2m Length 12 15.70 PlumbNation
10m Pipe Insulation 16mm - Blue 5 23 PSW Trade Suppliers
10m Pipe Insulation 16mm - Red 5 23 PSW Trade Suppliers
Sentinel Eliminator Quadra Cyclone Magnetic Filter 1 55.58 PlumbNation
STRAIGHT AUTO BYPASS VALVE 22MM 1 9.58 Screwfix
Female Elbow 16mm - 1/2'' 8 16.80 PSW Trade Suppliers
Pipeplus 15mm x 25m White Barrier Pipe 1 18.50 Plumbling and Heating Solutions
Pipeplus, G15SLE,15mm Plastic Pipe Support Sleeve 1 0.15 Plumbling and Heating Solutions
Calmag SI-CALCOMBI 15mm & 22mm Magnetic & Electrolytic Scale Inhibitor 1 33.70 Plumbling and Heating Solutions
Climaflex Pipe Insulation - 15mm x 25mm Wall x 2m Length 50 89.40 PlumbNation
22mm Manifold connector compression 2 7.20 PSW Trade Suppliers
WHITE & CHROME ANGLED TRV WITH LOCKSHIELD 15MM X ½ "  6 40.74 Screwfix
Straight Braided Filling Loop - Part L 1 8.97 Toolstation
Edited by MikeGrahamT21

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the only 16mm pipe insulation i've found is only 6mm thick, so I'm going to see how tight the 15mm fits 15mm pipe, and may use that. Any additions/improvements welcome :-)

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Climaflex 15mm will fit 16mm pipe. 

 

Question though - is this going under the floor as you’ve said you may have a vermin issue and they love eating insulation ....

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3 minutes ago, PeterW said:

Climaflex 15mm will fit 16mm pipe. 

 

Question though - is this going under the floor as you’ve said you may have a vermin issue and they love eating insulation ....

 

Yeah I know, i can't think of a cheap alternative though? Theres only a small chance of vermin, but i can live with them chewing through insulation vs pipe.

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Another thing I thought of last night, how on earth do you ensure the elbow is pointing the right way, or would it naturally fall that way?? Rubber washers inside the joint?

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I was going to buy stelrad softline compact radiators, based on what Nick (i think it was you) said on another post about them being good quality, but I've noticed that for the same size (i.e. 600 x 600) other manufacturers seem to have the same guarantee buy more output W, which potentially means I can get a smaller radiator for the same output. Would you stick with the stelrad?

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