Help with ancient system please.....

[cokeysblokey]

Hello this is my first post on here and it might be a long one

I have an open vented system that must be well over 20 years old running 4 radiators (2 up, 2 down) using a Baxi back boiler. I know that the best option is to replace it but the house is being renovated and extended so im trying to keep it running for another year or so when the extention is finished.

anyway, the system has a timeswitch that gives the option of HW/CH on or off only. the whole system stopped working a few months back, no heating or hotwater. I had a snoop around and i spotted the mid position valve looked to be the culprit. so i brought a Honywell V4073 valve to replace the ancient Motortrol unit. I presumed it would be a simple swap but things never work out like you plan, huh! after cutting off the old unit because it had corroded on i managed to rig the new one up. I then thought it would be a simple swap on the wiring but the old unit had 3 wires and the new one has 5! any idea how this should be wired?

I spoke to the people at Grahams down the road and we came to the conclusion that i could run the valve in the manual open position because as far as i can tell its not doing anything other than acting as a T junction. Unfortunatly the system still doesnt work. Ive taken all 4 rads off and flushed all the sludge out of them and replaced the pump as i wondered if this was the problem but still nothing. Hot water is getting to the pump but its not ciculating to and from the rads.

Now im thinking the fact that i havent got the mid position vavle wired up is causing the problem so im back to the 3 verus 5 wiring issue.

ive probably missed other bits of info but if you can help me it will be greatly appreciated.

Mark.

 

[Agile]

I think that you have missed quite a lot!!

One feature of a three port valve is that its always open to at least ONE port.

Most have a manual lever which puts them into the BOTH open mode.

It seems that your problem is not associated with the three port valve.

I would suggest the pump valves might be blocked or closed.

It seems very odd that after three weeks of pretty cold weather you have not apparently called a professionbal to sort out the problem.

Tony

 

[cokeysblokey]

Well if i cant figure it out soon the professional will be called, it just hasnt got cold enough for it yet

the pump valves? do you mean the isolators either side of it? if so they are fine. Also you have put my mind at rest about the 3 port valve although it doesnt help me much in finding the cause. im thinking there must be a blockage somewhere and its looking likely it needs a proper flushing. but would the system drain and refill ok with a blockage?

im just trying to figure it out myself......

Mark.

 

[Agile]

Just how do you "know the pump valves are OK" ?

How cold does it have to get before yuo call a professional?

A couple of weeks age it was around -1° C in the North!

Tony

 

[cokeysblokey]

i can only assume that they are ok as both are open and i cleaned them out so im guessing if they are open to full width they let water through. what else can be wrong with them?

So this is the checklist.....

Pump ok
3 port valve ok
rads drained flushed out
system refilled and bled (barring an airlock)

checklist of things to stop it working....

sludge/blockage in pipework
rad valves (but they probably are ok as HW isnt working either)
airlock
anything else???

evrything seems to fire up as normal and the water gets hot up to about 2 foot either way from the 3 port valve. the bathroom rad T's off before the 3 port rad and that doesnt get hot either.

I will call a professional but im fed up with paying people money to fix something i 'could' do myself and then finding out they did it badly that ive decided to try to do most things myself up until the point i cant go no further without outside help. When the house gets a new full system it will be done by a professional. I just thought this was a forum where people ask for help and people offered more advice than call out a professional?

 

[Alfredo]

OK..pin your ears back and engage brain.

Your Motortrol 3 port is a diverter valve and is PROBABLY wired for Hot Water priority..i.e. you rads will not get work until the cylinder is up to temp..It has three wires.

Your new Honeywell 4073 is not a diverter it is a mid position valve which can allow both HW and CH to operate together. It has five wires.

Provided you have both room stat and cylinder stat you can get the 4073 to work in HotWater priority mode as follows.
4073 5 wires
1) Blue to Neutral
2) Twist Grey and White together and connect to room stat wire(white is heating on/grey is HW off)
3) Green/Yellow to Earth connection.

This leaves you with orange (Boiler & Pump Live) left over..BEWARE**THIS IS LIVE** and you must trim it and seal it properly as it is not connected to anything.

Don't set your cylinder stat too high either or you can wait and wait and wait for your rads to get hot as its HW priority. 55c should do the trick.

IF YOU ARE NOT SURE.THEN DON'T EVEN TRY.

Let us know how you get on

Alfredo

 

[Slugbabydotcom]

Thats one expensive T piece you have there mister.

How do you know the pump is working ok?

I think that is what Tony meant to say

What I'm implying is that it may not be as ok as you think.

Is it noisy?

Have you taken the head off it and checked that the impeller is still attached to the armature?

 

[cokeysblokey]

thanks for the replies.....the pump is ok as its a new one. well i hope its ok with it being new. it isnt noisey but i will have a look at it later. i thought i could wire the port up like you say but needed someone to confirm this for me.

 

[ChrisR]

Glad Alfredo helped, rather than just taking the p___.


Blockages can be anywhere really, eg here.
Bleed the pump by removing the central screw.
Is it possible that debris blocked the pies when you "ground" the old valve out? Could it have jammed the pump? If there's a bad sludge problem it can block the circuit wher the feed pipe joins it, but then you normally get flow over the vent. If it can't because of too many blockages, try undoing a bleed valve on a suitable rad while the pump's on to see if it sucks air in.

It's quite likely that the resistance through your HW cylinder is much less than through the heating pipes, so all of any flow tends to go that way if the valve is in the manually open position.
An air lock on the pipe going into the cylinder will stop your HW.

 

[Agile]

.the pump is ok as its a new one. well i hope its ok with it being new. it isnt noisey but I will have a look at it later.

Just because its new it does not mean that its "OK".

It may be a faulty new one, you may have wired it up wrongly, it may be fitted wrongly, it may be jammed.

Have you checked that its bled as Chris says and that the shaft is turning?

Have you SEEN the open gates on the pump valves? Or do you just assume because you have turned the knob that its open?

Tony

 

[weareleeds]

Have you put pump in correct way round

 

[cokeysblokey]

Thanks again guys for the replies....the pump was brand new yesterday....i fitted it just before posting here. i have seen that both gate valves are open too and the pump is fitted and wired the correct way around. i have brought i new pair of gate valves as one has started to leak. i bled everywhere that there is a bleed valve...all 4 rads, the pump, and there are 2 bleed valves next to the HW tank.

Im 99.99999% sure its sludge.....black thick sludge, its everywhere. Im new to plumbing but my guess is that just because the system fills ok it can still not circulate as it back fills? ive just drained the system again to fit the valves and removed the length of pipe between the pipe and the 3 port valve and it had a lot in there. Now is there a way to DIY flush the system out?

 

[kevplumb]

are we talking "W" plan here

 

[cokeysblokey]

Well i think i have a little sucess

I found a blockage above the pump....i managed to pock some wire up there and free a good lot of sludge!!!!! at the moment i have a system thats flowing water....i can hear it i dont know how much of the system is getting heat yet but the HW side seems to be! i will be back in a bit after ive found out whats working and what isnt.

im slightly happier now...thanks for all the input

Mark.

 

[cokeysblokey]

Ok the B port side is getting heat...that means the HW and bathroom radiator. unfortunately the A side isnt getting anything yet. its hot from the port to where the pipe disapears under the floor but so far nothing is reaching and returning from the 3 rads on that side. one rad has a luke warm inlet pipe but not enough to heat anything. im thinking the feeds and returns are blocked. ive whacked the pump up to 3 to see if that helps force some water through but so far no sucess. there might be a chance of an airlock but ive bled the pump and all other bleed points repeatedly.

Mark.