Is there a difference or is it just the way they are plumbed in?
Cheers
Gav
Cheers
Gav
one pipe radiator vs two pipe radiator?
- Thread starter littlepigeon
- Start date
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The difference between a one pipe system and a two pipe system is that- on the one pipe system the water in the return of the first radiator goes to the flow on the second radiator, the return on the second radiator goes to the flow of the third radiator, (can anyone compose a tune to this? It's got the makings of quite a catchy song I think) the water in return of the third radiator goes onto the flow of the forth ...... I'm fed up now!! 
Whilst in the two pipe system the water in every radiator goes directly back to the boiler in order to be re-heated then directly back out.
Anyone still with me?
Whilst in the two pipe system the water in every radiator goes directly back to the boiler in order to be re-heated then directly back out.
Anyone still with me?
Yes, but you missed the chorus where we describe how there is a pipe loop running to and from the boiler with the radiators connected in parallel. In other words all the water does not have to flow through every rad.
Just to clear up any confusion.
Just to clear up any confusion.
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I mean each individual radiator. Do you have to buy a certain type of radiator or is it just the way the radiator is connected that makes it a one pipe or two pipe system.
I know the trvs are specific but are radiators specific?
I know the trvs are specific but are radiators specific?
D
daneski88
Any radiator will do. It's the type of thermostatic valves that need to be different (and thus more costly)
Rads are generally the same, but the valves required for a one pipe system need to offer very little resistance to the flow because of the very low, or non-existant pressure difference between the 'flow' and 'return' side of the radiator.
A one pipe system relies on thermosyphonic action within the radiator, aided by the frictional losses in a couple of metres of pipe, where a two pipe system can call on the full output pressure of the pump.
A one pipe system relies on thermosyphonic action within the radiator, aided by the frictional losses in a couple of metres of pipe, where a two pipe system can call on the full output pressure of the pump.
Many thanks for that.
One of my issues is my bedroom fails to get warm in winter. The radiator in there does look old but does get hot. The radiatoris a big one but is very thin , prob only about an inch wide at most.
What I'm wondering is can i just swap the rad out for a modern new one or is there other things i need to be wary of if its on a 1 pipe setup.
I was going to replace everything at once but i cant afford so i think I'm going to have to attack a room at a time. The bedroom being pretty important to sort before winter.
Cheers
Gav
One of my issues is my bedroom fails to get warm in winter. The radiator in there does look old but does get hot. The radiatoris a big one but is very thin , prob only about an inch wide at most.
What I'm wondering is can i just swap the rad out for a modern new one or is there other things i need to be wary of if its on a 1 pipe setup.
I was going to replace everything at once but i cant afford so i think I'm going to have to attack a room at a time. The bedroom being pretty important to sort before winter.
Cheers
Gav
As I read it you have a one pipe system fitted and you are saying you want to replace everything, is this correct?
If so and you do as you propose by changing one room at a time, are you just going to change only the radiators one by one and not the pipework or you wish to change the pipework to a two pipe system as well?
It would be very difficult to change the pipework at each room one at a time because you need to understand the system you have and what routes the pipes take and where to run the new pipes and join in at each stage so that it all works correctly. At each stage it would mean cutting into the old system and adding new pipework for the returns.
The way I would do it if I was in your situation would be to draw out a circuit diagram of all your existing pipework, where it travels around the property and then draw up a pipework plan of what you need for a finished two pipe system, then work out how it needs to be fitted at each stage so that the supplies and returns fully integrate. You will have to see where you need to lift floors at each stage to do that particular stage and what floors will need to be lifted at all subsequent stages so as to connect the pipework with the least amount of disturbance.
Another way to get it done is get a bank loan if possible and do it all at once, this would be the preferred way.
I would love to change the entire lot yes but at present i think i just need bigger rads to warm rooms better.
I really have no money to change the entire system and to make things worse we have just had all new carpet layed upstairs which i don't really want to be lifting
My main concern is warming the bedroom for which i think i just need a bigger rad as the one in there at the min gets hot but its an old very thin single panel radiator.
So if i was to tackle a room at a time putting in bigger more modern rads that i can have a bit of control over (all valves are siezed on the old ones) is it just a matter of straight swapping out or will i make no difference to the heat output?
I really have no money to change the entire system and to make things worse we have just had all new carpet layed upstairs which i don't really want to be lifting
My main concern is warming the bedroom for which i think i just need a bigger rad as the one in there at the min gets hot but its an old very thin single panel radiator.
So if i was to tackle a room at a time putting in bigger more modern rads that i can have a bit of control over (all valves are siezed on the old ones) is it just a matter of straight swapping out or will i make no difference to the heat output?
The problem with a single pipe systems as people have already mentioned is that the last radiator in the system will be the coldest as the heat has been taken from the water because of the path it has travelled, if the radiator that is giving you the main cause for concern is the last in line then by putting a larger radiator in there will not give you much more return in heat because the water in the rad will be at the same temperature as before.
If the system is old as you imply the radiators may be clogged causing the water to travel round the system slower than intended, I think it would be a good idea during the summer to drain the system, remove all the radiators and flush them through in the garden by flushing from both side and turning upside down and back over to clear the silt. (Be careful when removing the radiators and transferring them to the garden because the silt that is in the radiators will stain most surfaces that it comes in contact with and sometime it is very difficult to remove, cap the open ends and turn them upside down to move them) Whilst the radiators are removed it would be a good time to replace all the valves, they are not too expensive if you get the from PTS. A good way of telling how badly the radiators are silted up prior to removal is to feel around the bottom of the radiator when the heating is on to see if the central area of the radiator is colder than the rest.
If the system is old as you imply the radiators may be clogged causing the water to travel round the system slower than intended, I think it would be a good idea during the summer to drain the system, remove all the radiators and flush them through in the garden by flushing from both side and turning upside down and back over to clear the silt. (Be careful when removing the radiators and transferring them to the garden because the silt that is in the radiators will stain most surfaces that it comes in contact with and sometime it is very difficult to remove, cap the open ends and turn them upside down to move them) Whilst the radiators are removed it would be a good time to replace all the valves, they are not too expensive if you get the from PTS. A good way of telling how badly the radiators are silted up prior to removal is to feel around the bottom of the radiator when the heating is on to see if the central area of the radiator is colder than the rest.
I will give that ago although the radiator for the bedroom isn't exactly luke warm or anything, it gets really hot to touch and seems to be hot all over. Thats why i thought i just needed a bigger radiator. The rooms are 2.7m high and this room does have two external walls with no cavity as its an old edwardian house.
I guess my next question then would be where is it that i would drain the system? is this done at the boiler?
I have an old system, open vented i think its called. I have to tie up the ball cock in the loft don't i so it stops it filling but is there anything else i should be wary off when draining or refilling?
Many thanks for your comments so far this is a great help to me.
Cheers
Gav
I guess my next question then would be where is it that i would drain the system? is this done at the boiler?
I have an old system, open vented i think its called. I have to tie up the ball cock in the loft don't i so it stops it filling but is there anything else i should be wary off when draining or refilling?
Many thanks for your comments so far this is a great help to me.
Cheers
Gav
Your guess would be as good as mine to the whereabouts of the drain point, it should be somewhere at the lowest part of the system usually near an exit point of the house but I have found them in some really weard places. As for draining this is usually quite straight forward as soon as you have located the drain off point. attach a garden hose to the drain and pass it to an outside drain, Turn off the feed to the topup tank, undo the drain valve (not too far or else it will come apart, you can here when the water starts to flow) and wait do the system to drain down. Dont assume all of the water is out of the system because air locks and the way that the pipework has been run may catch you out so always be aware when releasing any fittings. When topping up it as yours is a single pipe system ensure all the radiator valves are fully open and bleed each radiator in turn with the closest one to the topup supply first.
I think it is the single pipe system described here, useful in old hospital wards and governed by valves on the beginning and end of each circuit.
A one pipe system is very good when designed well with each radiator flow and return taken off the same pipe in series. It needs larger pipework to carry the mass flow rate and more careful balancing on the lockshield but will give even temperatures through all the radiators albeit the last ones take a little longer. No problem in a domestic property or zoned larger properties.
Not as good or forgiving as a two pipe.
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