Problems with 2 x new rads not heating up.

[rolyberkin]

First off I am sparky so go gentle ;-), I have been involved with a garage conversion with a builder friend and we have added two small rads to the existing system in a garage sized room with a small wc. I have sought the assistance of a plumber friend who is coming to look on Tuesday but in short this is baffling me.

The existing system is an open vent s plan with a combi boiler, the boiler was changed from a conventional boiler about 4 years ago and resited in an upstairs bedroom, the storage tank is also on the first floor. The two zone valves are some way from the boiler in a different room in the old airing cupboard.

Took these in 15mm off 22mm flow and returns with full bore isolators run is about 5m, finished the job and filled up and we cannot get the rads to heat up, there are problems with the existing system in that a downstairs plinth rad and rad in the lounge do not get hot and according to customer the plinth rad has never worked. Customer says the system was flushed last year but when we tried to drain from the plinth rad and lounge rad only a trickle is coming out, think these pipes may be silted up/partially blocked?

There is a towel rail in a bathroom about 2m from where we took our branches from and this is working fine. If we turn off all rads our new rads do not heat up. The two rads below the boiler are heating fine

I have flushed the two new rads through by attaching a hosepipe to the return and letting the water from the flow go through the rads, they then instantly heat up. The rad in the bedroom above our conversion is also getting luke warm.

I am baffled in that if the towel rail by our branch gets hot why aren't our new rads heating when all other rads are isolated?

My thoughts are, does it need an aditional pump near the zone valves, is there an airlock in the system or has someone bodged the flow and return pipes near to the boiler so they bypass the links to the zone valves?

Any suggestions appreciated?

 

[Scott_D]

Is the heating side open vented?
Where have you teed off for the new rads? After the heating zone valve?

 

[rolyberkin]

Is the heating side open vented?
Where have you teed off for the new rads? After the heating zone valve?

I think the heating and water is closed loop just the feed for the old style hot water tank is open vented, if this is the correct terminology, we have teed off after the heating zone valve.
[automerge]1570976930[/automerge]
I am sitting here wondering if the hot water zone valve is stuck open?

 

[Jones82]

Possibly piped up wrong? 2 flows and 2 returns, so no circuit?

By that I mean you should have a flow and a return to each rad and instead you have 2 flows and 2 returns. Seen it done before

 

[rolyberkin]

Possibly piped up wrong? 2 flows and 2 returns, so no circuit?

By that I mean you should have a flow and a return to each rad and instead you have 2 flows and 2 returns. Seen it done before

The same flow and return goes to a towel rail about 2m away from the spur point and it is working? Also only one is primarily getting hot the second once the towel rail heats up!?

 

[SavageW]

Plinth rad if I’m correct in thinking like a kick space heater in kitchen are normally on flexi hoses which block up, when you say you’ve taken the flow an return from the 22mm you have run a pipe to flow of radiators & then run a separate pipe from the 22mm return to the radiators? Otherwise sounds like could be one pipe system

 

[Jones82]

Perhaps the valves are faulty? Maybe try taking the new radiators off leaving the closed valves, then open the valves whilst connected to some hose pipe to flush through and ensure you have a good flow, from both valves/ I'd also be looking at the colour of the water, if it was flushed last year it should be clear. If all of this is good Id be looking in the pump

 

[rolyberkin]

Plinth rad if I’m correct in thinking like a kick space heater in kitchen are normally on flexi hoses which block up, when you say you’ve taken the flow an return from the 22mm you have run a pipe to flow of radiators & then run a separate pipe from the 22mm return to the radiators? Otherwise sounds like could be one pipe system

Although the system was supposed to have been flushed last year yes I think the plinth kickboard rad is well and truly blocked and the rad next to it is also not heating up, it doesn't look like a one pipe system as the other rad nearby to the 22mm pipes we have come off is piped one side off each pipe and there are two 15mm pipes at the end of the 22mm going towards an upstairs bedroom (the rad in there is also not getting that warm also!). I have flushed the new rads direct from the boiler feed and am getting good flow through the rads, when we took off the return at the point of connection and flushed through they both heated up immediately, I wondered if the pump was playing up or else the two port valve for the water cylinder was stuck open with the flow using this as an easy loop and back to the boiler? Will report back on Tuesday after we have had another look?