brand new boiler, rads, all pipework..very very slow to warm rads

[Alexxx]

Hi Folks,

Sorry, long post with hopefully a good explanation of what has occured. Renovating a 1933 building, two storeys, 3 bedrooms up stairs, one large room downstairs with two smaller rooms at the end of the large room. Removed every trace of ancient boiler systems.
Professional plumber fitted all new15mm water and radiator pipework, brand new Kudox rads from screwfix and I bought a brand new worcester Bosch 35 combi boiler, professional gas guy fitted 22 gas pipe feed and commisioned the boiler.
Had an issue with the plumber guy disappearing for weeks to do other work so had to ask the plumber on the building team to finish the work.. Original plumber laid pipes in a messy fashion and did not put in any radiator drain point or valves to isolate upstairs and downstairs so the builder team sorted that out.
Upon running the heating system for a few hours we could get no heat in the rads so I had a look under the ground floor as all that pipework was visible.
There was a loop connecting the combi output with the return flow that had to have a stop valve in it as any hot water output just returned by the loop letting the boiler think all was up to temp.
Water then got to some of the rads, mostly upstairs, I then found out about rad balancing and done my best by testing which rad heated first and also which end was the hot water going in the rad. I set the thermostatic valves for the correct flow (some correct by luck, no one had checked). Got all the upstairs warming but never hot. Had to close all upstairs valves to get hot water to flow to ground floor rads, eventually got all balanced with fairly even heat output but it was never more than warm. After running for a day, all would become hot but you could still put the back of your hand on any rad and keep it there.
Got the gas engineer out thinking it must be a faulty boiler , he checked alkl and confirmed the boiler was working correctly. He suggested letting it run for a few days but we are 30 miles from the property and only there weekends just now.
I started the boiler today, run it for 4 hours and the ground floor rads never even got warm, just better than cold, upstairs got a wee bit warmer but still useless.
I would really appreciate some advice as I am burning gas at full power but getting nothoing out the heat system.
If I check the output pipe from the boiler it is very hot (likely the 70 deg C as set) but the return is luke warm.
I can see under the ground floor that the hot output is not daisy chained but a single 15mm pipe with a feed to each rad via a T piece same with the return system.
I have no idea with the setup is under the upper floor as all is floored now.
I'll try post pics of the ground floor pipework later.
I'm trying to get the original plumber back but seems he has given up business and mostly working for a large company on a contract basis, hopefully he can get out and help but in the meantime...help!

 

[terryplumb]

If 15 mm pipe runs to all your rads ,without branching from 22 mm to each rad, then it's badly installed,even more so if pipework is plastic not copper.
The pump would be the first suspect if the boiler is producing water at 70c and it's not getting to the rads. Always assuming the boiler is functioning correctly as the engineer has apparently confirmed.

 

[Alexxx]

Thanks Terryplumb.
I am suspecting pipework, should it be 22 from the boiler then branch off in 22 going to 15 just before the rads?
I think the boiler rad water output is for 15 but it could then go directly into 22?
The gas engineer tested the pump and all boiler functions, all good.
There are some long pipe runs at the ground floor, about 10m long feeding just 4 rads ( going to be a cafe not a home so don't need to go mad)
Is the normal spec to run all in 22 going to 15 just befor the rads?
The pipe work comes out the boiler in 15 then to a 15mm tee (about 4 m from boiler) which feeds water upstairs and then down to under ground floor, all in 15.
It could mean I have to remove all upper flooring...damn..got laminate down then 6mm ply over floor boards, can't bear to think about that yet.
I was always concerned about getting the plumbing right as that what what destroyed this old building in the past. I asked the plumber to check all before I laid the floors as I know how dementing it would be to lift all that good work.
He pressure tested the system and gave the go ahead. I did notice he was pushing open end pipe through the floor debri but he blew them out before fitting, I would have plugged or taped them but I have to assume all is clear and good.
I relied on a plumber as I know I dont have the experience to design a fresh new system.
At least here I can get a consensus on how my system should be designed...22 most of the way ?

Thanks

 

[terryplumb]

Show us pictures of pipework Joining boiler. I find it hard to believe that 15mm pipework has been used for flow and return pipework from boiler. 15 mm would be normal for the domestic hot water ,from a combi.
How many radiators in total are on the system , and what sizes are they ?

 

[BlueLoo]

Draw the system out.
Show it to the trades here.

 

[akist]

Not a plumber, and am learning as I go, but if the flow is boiling hot and the return is just warm, and no radiators are even hot, then something is using up all that heat, where is it going? The hot water cylinder perhaps? Or, what if the pump is real slow and the flow does not reach remote rads so only heats up the few rads it can reach?

 

[Alexxx]

Thanks folks,
I'll take photos and sketch out the system. Rads are a combo of sizes from 600 to 1200 double panel, Ill get the exact spec later.
4 rads downstairs and 5 rads upstairs plus a bathroom towel rail so not many. the three bedrooms are small, about 4m x 3m or less.
No rads in the kitchen, the upstairs living room has the largest rad.
Sometimes you can feel the section of radiator near the output still cold, it seems as if flow is extremely slow everywhere.
If I leave the system running for a whole day everything becomes hotter after 6 hrs or so but not as hot as normal.
As I said everything was brand new, I am now thinking perhaps I should have run a hose through the new rads but I've never had to do that before and I expect the manufacturer would have ensured clean construction.
There is no hot water cylinder or cold water tanks, everything is run from the combi which gets its feed directly from the mains (new and excellent pressure)

 

[JohnD]

I set the thermostatic valves for the correct flow

You do not (should not try to) use TRVs to adjust flow and balance the system. It will not work.

You use the lockshield valves on the other end. That's what they're for.

When balancing, close all the lockshields, and open by half a turn. No more.

Then run the CH for half an hour.

Use the temperature sensors in the skin of your hand. The flow pipe should be "too hot to hold" and the return pipe should be "too hot to hold for long."

For any that are not, open or close the lockshielc by no more than a quarter turn, and continue running the CH for another half hour before checking again. Do not alter any by more than a quarter turn in half an hour. The adjustment is very slight, and it is all at the "nearly closed" position.

Once flow seems correct, and has been for half an hour, feel them all over. Top, bottom, sides, middle. There should be no cold patches. They should be hotter at the top than the bottom. If any are excessively hot, you can tighten the lockshield by a quarter turn.

Some rooms may have rads that are too big, and you can reduce their output by tightening the lockshield. A radiator that is too small for the room cannot be made more powerful.

Write the adjustments in a notebook and tie it to the boiler.

 

[Alexxx]

Thanks all
Advice much appreciated
I meant to say lock shields that is where I carried out all adjustments as has been advised. Started with all closed and adjusted throughout the day. Most are about quarter to half turn from closed. I think the huge problem is the all 15mm pipe work inc from boiler. I’ll get pics and sketches during the week.
Appreciate the experienced advice thanks all

 

[Alexxx]

Got a couple of pics of the boiler and its pipework from my phone.
The boiler guy fitted 22mm copper for rad flow and return about 500mm and left the rest for the plumber who fitted all 15mm plastic from there on.
Another pic shows pipewrok from the boiler coming into a tee to split upstairs and downstairs along with hot water and cold mains which is valved.
I did ask for valves on all so I could easily do future maintenance but the plumber fitted none, that valve was fitted after.
I also asked for a split between upper and ground floor so I could isolate either, never got that. I also had to have a drain fitted later as he never done that either.
Basically looks like the lack of 22 flow and return is to blame. (especially the return going into 22 just before the boiler, that would slow flow down?)
I can easily do all from the boiler to below ground floor and maybe a wee bit in 22 (flow and return) before it goes to upper floor, I would like to know if doing all that it would still have a positive (hotter) effect for upstairs? I ask as I do not want to dig up all the flooring. I am sure the plumber only fitted all 15mm upstairs.

 

[JohnD]

"Plumber," you say?

 

[BlueLoo]

Holy ****.

 

[BlueLoo]

I'd rip it all out tbh.

 

[Exedon]

That is truly dreadful that guy's never a tradesman.

 

[Mottie]

That is absofuckinglutely terrible. Rip the lot out and start again. FFS don’t pay the bloke (or is it too late) .