Can radiators be piped from above?

[Colin Green]

It would be an odd question for a house, but I'm considering adding radiators to a narrowboat and it would be easiest to fit the pipes under the gunwales and drop them down to the radiators. Can the check valves be mounted to the top ports and the bottom ports be blocked off / have a drain plug? I know they physically could. Is there a reason why it wouldn't work well?

 

[ericmark]

I seem to remember my son fitting central heating to a narrow boat, it required 12 volt pumps, with automatic change over should one pump fail, and uses a special boiler that ran on 35 sec gas oil not 28 sec, and loads of other special features.

Basic idea is hot water is lighter than cold water, so as it cools it will drop, so hot in at top and cold out at bottom, so natural flow assists the pump, but pipes need lagging for that to work, so often both in and out are at bottom, but since a narrow boat often has a solid fuel aga or similar which will not auto switch off when water gets too hot, basic a multi-fuel central heating system, using engine cooling water, aga hot water and a diesel heater, there are a lot more safety features required to a system fitted in a house.

This often includes a radiator pressed against to hull to cool water if it gets too hot, and it needs to comply with RCD. It is a long time ago when my son had his, and a lot has changed, the best place to ask is a narrow boat forum, as it is rather specialist, and the RCD will not allow you to do same as one would do in a house. RCD = Recreational craft directive.

 

[Ivor Windybottom]

Short answer... No. They're dependent upon the incoming water being warmer than what's already inside, so it rises and generally swirls about until the entire panel is hot. If you squirt hot water into the top of a cold rad with an outlet pipe on the other side then it will just shoot straight across the top and leave the rest cold. In fact this is how hot water cylinders can be set to only heat some of the contents, they rely on the hot water staying at the top and not mixing, and it works surprisingly well.

Longer answer... Yes. You can pipe from the top of the wall, drop down the back of the rad and into inlet and outlet valves at the bottom of the rad. It works well with tall rads, in which case the pipes will be invisible other than a slim bit of trunking above. This requires very careful selection of the rads, especially the spacing from the wall and low-profile pipe clips down the wall. I'm currently planning a home install and am hoping to find a plumber capable and creative enough to want to do this.

If you're interested I've mocked up a prototype using bits of wood, pipe and brackets, I can upload photos if you like. I can't see why this couldn't work, but I'm not a plumber.

 

[Colin Green]

Short answer... No. They're dependent upon the incoming water being warmer than what's already inside, so it rises and generally swirls about until the entire panel is hot. If you squirt hot water into the top of a cold rad with an outlet pipe on the other side then it will just shoot straight across the top and leave the rest cold. In fact this is how hot water cylinders can be set to only heat some of the contents, they rely on the hot water staying at the top and not mixing, and it works surprisingly well.

Longer answer... Yes. You can pipe from the top of the wall, drop down the back of the rad and into inlet and outlet valves at the bottom of the rad. It works well with tall rads, in which case the pipes will be invisible other than a slim bit of trunking above. This requires very careful selection of the rads, especially the spacing from the wall and low-profile pipe clips down the wall. I'm currently planning a home install and am hoping to find a plumber capable and creative enough to want to do this.

If you're interested I've mocked up a prototype using bits of wood, pipe and brackets, I can upload photos if you like. I can't see why this couldn't work, but I'm not a plumber.

This makes a lot of sense, thanks.

 

[Ivor Windybottom]

I read on the internet that someone used to make a top-inlet radiator that includes an internal guide/baffle that routes the incoming water down to the bottom as it enters, effectively making it a hidden bottom entry one. But I couldn't find anywhere that actually makes or sells such a thing, if anyone knows better then please shout.

It's OK or even desirable to have the outlet at the top anyway, some even say this is best practice. I don't know, but it's definitely acceptable.

 

[sjmac]

STELRAD Vita Deco and a fair few others allow top entry.

Care needs to be taken to ensure both pipes can be vented

 

[Ivor Windybottom]

I asked them about the option of top connections. I don't know whether the water is actually routed to the bottom internally, I suspect not. Also I pointed out that a TRV mounted at the top would get warm and cut off almost immediately due to the rising heat from the rad. They didn't argue, and didn't seem to offer any explanation of how it's supposed to work. Unless I'm missing something I don't get how this would work.

I'm planning to use their radiators, but using the centre connections at the bottom with the pipes behind the rad.

 

[Ivor Windybottom]

My mockup of my plans. I'm waiting to find a plumber who says whether this can or can't be done!...

I've just used plastic pipes for my mockup, in reality it would be copper. The elbows are press-fit, as they are the only ones I could find that give sufficient reach, and they look neater than compression.

The clips and trunking aren't the standard Talon stuff you get at every supplier, they're too tall to fit behind a Stelrad radiator. They're some other brand that's really hard to find. I'll try to remember whose they are. The trunking clips onto the brackets, it won't fit behind the rad so it would need a trimmed length a short distance from the top of the rad to the ceiling.

I can't see why this wouldn't work, and it would be vastly neater than the standard way of having pipes banged along the top of the skirting boards and up the corner of the room.

 

[Justin Passing]

It doesn't matter!! You aren't relying on convection to circulate the water, you have a circulator pump which generates a pressure across the rad far higher than that caused by the differential density of the water in the pipes.
Loads of houses with concrete floors have pipes dropping from above, to the ground floor. They still work if the pump's in backwards!

Not sure what your yellow sheet is @Ivor Windybottom? You can't cover the TRV of course.

 

[Ivor Windybottom]

The orange sheet is the thickness of a Stelrad tall double radiator. The jutting out extra bit is the spacing from the wall. The TRV is under the rad. Not ideal, but vastly preferable to it being above, even if off to one side.

Also, as I've already stated, the TRV will just shut off if it's fitted above, as it will be about 30 degrees as soon as the rad gets warm.

Most houses with solid floors have the pipes coming down to the skirting then up into the rads. I don't think anyone normally plumbs into the top of them.

 

[Ivor Windybottom]

This is the crappy standard way of doing it...

 

[Ivor Windybottom]

However it's piped, you need one or more bleed valves up above, wherever the high points of the system are. There are automatic bleed valves, but many say they frequently leak.

 

[Fred Blogs]

Again my 30 odd year old 8mm microbore heating is piped from above because we have concrete floors. It isn't very pretty I will admit but it works. I also had a narrow boat before I moved to this god forsaken place called wales (only because it's where my family are) and whilst the central heating pipes on that were below the floor I know of two or three that are piped from under the gunwales. There is a bit more to plumbing stuff in a narrowboat but I suspect you know that.

 

[sjmac]

I asked them about the option of top connections. I don't know whether the water is actually routed to the bottom internally, I suspect not. Also I pointed out that a TRV mounted at the top would get warm and cut off almost immediately due to the rising heat from the rad. They didn't argue, and didn't seem to offer any explanation of how it's supposed to work. Unless I'm missing something I don't get how this would work.

I'm planning to use their radiators, but using the centre connections at the bottom with the pipes behind the rad.

To use top entry you flip the rad and effectively fir upside down, the internal flow pipe injects the water to the bottom as it would to the top in a normal install.

If I was installing with top entry I would use remote sensing TRV's or left and right tapings with the head turned out from the rad.

If you are using Vita Decos, what the point of the trunking, its all behind the radiator. Just clip 15mm copper to the wall and use corner entry rad valves ignore the centre valves, especially if you have lots to do ££££

 

[Ivor Windybottom]

If you are using Vita Decos, what the point of the trunking, its all behind the radiator. Just clip 15mm copper to the wall and use corner entry rad valves ignore the centre valves, especially if you have lots to do ££££

The trunking is just for the short section between the top of the rad and the ceiling. Otherwise just the clips that the trunking normally clips onto. Exactly as shown by my model in fact! Obviously it's not as tall as an actual room, but illustrates the top and bottom minus the featureless middle.

Please explain how you think you'd pipe to the side valves. You'd need pipes spewing out from underneath somehow, and going upwards into the valves. I can't imagine a way it wouldn't look a right mess. The centre valve connects pretty much directly to the pair of pipes running down the centre. Although not ideal, the air should be drawn in from the room before rising up within/behind the rad, so the TRV should be mostly sensing the room temperature rather than the red temperature.

Not slightly worried about the extra cost of centre valves, it's trivial in comparison to the cost of the rads, pipework and £5000 heat pump.