Radiators won't warm up

[dave163]

I live in a three storey Victorian terraced house. The previous owners fitted central heating to the ground and middle floor but for budget reasons did not heat the top floor. However their layout supposedly allowed for the possibility of taking a loop to the top floor and the boiler has adequate power. So when I first bought the house I got a plumber to fit radiators to the top floor, taking two half inch copper pipes up through the floor and up along the wall inside the cupboard under the upper stairs to get to the top floor. Then I had the whole middle floor covered in laminate flooring which would be a total *£$& to lift. I don't know where he connected the two pipes to however.

The floor plan is shown in the diagram. I have shown cold radiators in blue, slightly lukewarm yellow, hot pipes as yellow and very hot pipes as red.

The radiators in the front bedroom and ensuite bathroom have never worked, though when the heating is on full one or other of the pipes from the floor to both radiators is slightly lukewarm. The radiator in the hallway gets blisteringly hot, the radiator in the back room is pretty hot too and the radiators on the top floor get quite warm. One of the two pipes going up the wall inside the cupboard is very hot, the other is quite hot. The previous occupants did confirm to me that when they only had the middle floor heated, the front room radiators heated up fine.

I have had several plumbers take a look and offer lots of opinions. All have tried balancing the circuit to no avail. One wondered if the top floor had been plumbed in a way that robbed the middle floor of hot water. One fitted a shunt between the two pipes going to the top floor - that's been removed as it only stopped the top floor radiators from working! One even wondered if the plumber that fitted the extra radiators might have fitted a valve under the floorboards wherever the pipes leave supply the top floor and left it half shut. A limited amount of water seems to flow to either of the two front radiators but not enough to warm them up.

I've been able to remove a small amount inside the under stairs cupboard (blue circle) and take up the floorboards in it to have a look and feel with an endoscope. It looks like both pipes that go up to the top floor turn and go forwards into the front bedroom where they must presumably join the original circuit somewhere. I can also feel two quite thick pipes (maybe 3/4 inch? - but a bit thicker than the 1/2 inch pipes that go up the wall to the top floor). These run along the hallway into the front bedroom and presumably come from the vicinity of the hallway radiator. With the central heating on, one gets very hot and the other fairly hot. The pipes coming from the top floor actually pass under these thicker pipes before turning to run parallel and adjacent to them into the front room but they do not connect near the cupboard under the stairs.

I don't know how the rest of the middle floor circuit is arranged so don't know how the back room is supplied or whether it's on a loop that goes from the hallway radiator and into the front room for instance. Also, I don't know where the pipes supplying the bathroom hot and cold taps run as I can't see or feel them under the floorboards through the access hole I made; they presumably run more centrally to the house. (I did run hot water tap when feeling the pipes before turning that off and turning on the central heating.)

I really don't want to have to get the whole middle floor up to check the layout of the heating pipes unless absolutely essential to either diagnose or fix the problem. For all I know it might be an airlock or silt in a radiator.

Next time I call a plumber, is there anything else I should ask them to check for and work through prior to sucking it up and taking the whole house to pieces?

And based on the information in the jigsaw puzzle provided, does it sound like I can have hot radiators on both middle and top floor without dismantling the house to correct a bad plumbing job, if that's what has happened?

 

[foxhole]

Could not see any reference to floor level with each radiator mentioned which makes it difficult to understand post.

 

[dilalio]

Can you get the cold rads hot if you shut down all other rads?

 

[Madrab]

Where is the boiler? Ground Floor? How many other rads are there? You may be near the limit of what can be fed by 15mm @ a height of 5-6m, which the top floor would be from the ground floor I'd guess? A good balance would probably help if, 2 of the rads are hot.

 

[dave163]

The floor plan is rhe front and central part of the middle floor of the house, I didnt show there is,also another bathroom and bedroom to the right of the plan. There are 13 radiators in the house, which I'm told is fine for the size of boiler. Most of them work fine, it's just the two in the front bedroom that don't come on despite multiple attempts at balancing. The red and yellow circles in the cupboard under the stairs going to the top floor represent the vertical pipes going to the top floor.

Boiler is on the ground floor. Even if all radiators are turned off except the front bedroom and ensuite (and one flow though downstairs that can't be turned off), the front bedroom still won't heat up.

Any suggestions besides balancing, since that's been tried countless times to no avail?

 

[dilalio]

Even if all radiators are turned off except the front bedroom and ensuite (and one flow though downstairs that can't be turned off)

Then this suggests several potential causes.

Blocked pipes to those rads.
Incorrect piping to those rads.
A never opened isolation valve(s).
Pump inadequate to overcome resistance.

Do you have an auto bypass installed? The resistance of the runs to the cold rads could be causing this to open up and short circuit the F&R.

The rad that you can't shut off could also be acting as a bypass. Need to get that adjustable would be first thing as it could be robbing most/all of the heat... Does it get too hot to touch?

Take one of the cold rads off and see if you can get flow out of the tails, into a bucket etc.

Also what size expansion vessel do you have? One in the boiler is not enough for that number of rads and head!

 

[Johntheo5]

The floor plan is rhe front and central part of the middle floor of the house, I didnt show there is,also another bathroom and bedroom to the right of the plan. There are 13 radiators in the house, which I'm told is fine for the size of boiler. Most of them work fine, it's just the two in the front bedroom that don't come on despite multiple attempts at balancing. The red and yellow circles in the cupboard under the stairs going to the top floor represent the vertical pipes going to the top floor.

Boiler is on the ground floor. Even if all radiators are turned off except the front bedroom and ensuite (and one flow though downstairs that can't be turned off), the front bedroom still won't heat up.

Any suggestions besides balancing, since that's been tried countless times to no avail?

What make & output gas or oil boiler?, Sealed or OV?, is the circ pump external to the boiler and if so make/model/mode/setting.

 

[HERTS P&D]

Why do you want the heating on in this weather?



Andy

 

[dilalio]

Why do you want the heating on in this weather?



Andy

Gets cold on 3rd floor - it's the altitude!

 

[dave163]

Haha, I don't need heating on at the moment. Just a convenient time to do odd jobs like lifting floor in a storage cupboard which helped me map out some of the pipework, and maybe heating engineers are less busy in summer.

Answers to other questions - British Gas 430i boiler (rebranded Worcester Bosch) which heats central heating and domestic water separately to a hot water tank (ie not a combi). Probably 15 years old. If it simply isn't powerful enough or if it has an inadequate pump (do all central heating boilers have a pump) it would be due for replacement eventually, probably similar type as already got a tank and house might be on the big side for a combi. But I've been assured it is designed to cope with 13 radiators (two of which are towel rails) on three floors.

There are two unvalved or free flowing radiators both on the ground floor.

No idea re auto bypass, size/location of expansion vessels/size of pump.

Several plumbers have looked at the system (without lifting floorboards) and tried balancing different rads to no avail. The last one said I needed all the floorboards up in middle and front room to see if there was a blocked valve or if the pipes to the top floor might have been spliced into the circuit in a way that robbed the other rads. I don't want to go that route without ruling out other less destructive options first.

In particular Dilalio thank you for suggesting those ideas - sounds like there may still be more to test and possibly tweak before getting to digging up floors.

One other thing - foraging under the floor in the cupboard I found the two 3/4 inch pipes that go into the front bedroom and presumably are meant to supply the front bedroom/ensuite rads as well as the top floor rads. These travel from (and back to) the boiler which is at the rear of the house. As well as supplying the top floor and middle floor front bedroom (well, in theory), they also supply three of the downstairs radiators.

When I felt under the floor with heating on, they were hot. When they get closer to the ensuite, they must have a downwards spur as there are two pipes running down the wall beside the front door on the ground floor. (The front door is directly under the ensuite.) These pipes supply the living room (under front bedroom) PLUS the ground floor hallway radiator which is one of two unvalved, free flowing radiators. (The other free flowing radiator is the kitchen towel rail at the back of the house next to the boiler.)

I don't think we ever tried balancing or cutting the GROUND FLOOR free flowing radiator off, but if we could close that, plus turn off the other ground floor rads and turn off the top floor rads, I wonder if that alone could get the front bedroom rads to start working? If so, how would we avoid reverting to blocking off the flow to the front bedroom whenever we turned on the downstairs hall radiator?

TLDR: I've established that two pipes, "from boiler" and "to boiler' go under the middle storey floor into the front bedroom, and are hot when the heating is on.

As well as supplying the front bedroom/ensuite, from these two pipes come two pipes to make the top floor circuit, and two pipes to the front room and hallway of the bottom floor of the house (whose circuit includes a free flow radiator). When the top floor pipes got plumbed in, the front bedroom and ensuite rads stopped working, though they do appear to be filled with water. I want to get them working, if possible without having to take up the whole bedroom floor to do so.

 

[briwire]

Try shutting off all radiators except the ones on the top floor. If they still don't get warm, they never will do.
In that case, look at your pump to see if it is powerful enough to force the water to that height. You might need to replace it with one of a higher flow.

 

[dave163]

Thanks, it's the rads on the middle floor that stay cold; top floor get quite hot and ground floor get very hot. But next step sounds like we need to block all ground floor radiators that are supplied by the pipes that goes into the first floor front bedroom, and all the top floor radiators too.

If that doesn't work, could we test for a blockage versus incorrectly plumbing the top floor without lifting more floor up? E.g. if we drain the system and remove the front room radiators, could we test those radiators for signs of obstruction, and would you pour water into the pipes supplying them to see if it drains? Just trying to think how to narrow down the cause and avoid moving loads of furniture and lifting laminated floor unless absolutely necessary, or at least pinpoint which bit of floor to lift to diagnose and fix.

 

[Johntheo5]

What might give you some idea of the middle floor problem is,....... with the boiler off, on any one of those rads, crack open the rad vent to get a smallish stream of water into a container, then start the boiler and see does the stream of water increase or decrease, if it increases then might point to a return pipe restriction for whatever reason, if it decreases then possibly some restriction on the flow side, boiler may require topping up later after tests.

 

[dilalio]

Get a power flush connected and test circuit to the problem rads.