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eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Hi

wondered if anyone can give me some advice. I've had a couple of central heating engineers out now (British Gas, and also a "good" independant) and they seem to be a bit baffled as to what the problem is.

Have a myson orion standard boiler (not combi or pressure), can operate central heating and hot water alone or together.

to cut a long story short, I am due to move house in about 8 weeks so dont really want to fork out for a new boiler or have a power flush as both heating engineers seem to be a bit baffled as to the problem but think that either / or power flush and new boiler (with power flush prior to it being fitted) will fix the issue, but this problem is driving me mad.

Basically I have been having probs with central heating for a while now, rad's not fully heating up etc. Going back a couple of years (maybe a little more) the pump on the central heating was noisy, central heating engineer said needed replacing, that fixed the problem.

Since then had bathroom re-fitted. Admittedly when water was drained out of system I didnt put any inhibitor back in it, and since the bathroom was re-fitted hasnt really worked properly. No changes to central heating system or pipework etc (other than changed rad for towel rail) but the central heating pump (or so I thought) seemed to be making a noise so we changed it again - like I said before other one was probably 2-3 years old max. Anyway, looking back on at that time that it was probably more the boiler making a noise than the actual pump. The independant central heating engineer came out and suggested some silencer, which after being in the system a few weeks did make a big difference for the central heating, all rads now work and heating up ok.

However, I still have an issue when the hot water timer comes on to heat up hot water if the central heating is still on. When just heating alone is on it works fine, more or less quiet (odd time you do hear it) but when hot water is on at same time, it becomes really noisy and the rads get cooler. Also, when both on at the same time, the pump does actually make noises, and the whole heating system seems fairly noisy. We though this may be the two way valve so replaced that too and it doesnt seem to be that thats an issue.

i've discussed in some length with central heating engineer, have flushed out all rads with hosepipe and all rads get hot, so doesnt seem to be a blockage anywhere. Also boiler is now fairly quiet, its just the issue of the pump being noisy when hot water on with central heating. The heating engineer did mention that sometimes when you fit new pumps the valves inside that connect to the pipe can get stuck, but he didnt think that was the case so all he can do is power flush the system.

do you think its worth me trying another central heating pump? It just seems odd that its noisy only when the hot water comes on when the heating is on, it has an automatic pressure adjustment, but seems to switch between high and low pressure like its trying to force the water through somewhere when both water and heating are on. I dont actually think its a boiler issue as the silencer seemed to work well, and also seemed to cleanse the system and sort out cold rads problems.

Does anyone have any suggestions?

Many thanks

AlanE · Posted: Sun May 04, 2008 10:43 pm Post subject:

eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Alan - thanks for you reply (I really appreciate the help)

Pump is a WILO smart 26/6(?) (from B&Q), it has 3 settings on it, one for single storey, one for double storey and one for triple storey, however it seems to be self regulating (ie if you put it on the 3 storey one it starts pumping faster but then settles down to the same speed as it does if you have it on the two storey setting).

Motorised valve is sunvic SDM 1901, dual valve (unishare hot water port b, heating port a)

Sorry, cant find any more info on the boiler model, and cant seem to get the front cover off to check. Its about 14 years old.

Its a 4 bed house, 11 rads in total (inc one towel rail)

The noise isnt a banging, more like a whirring/rushing. Similar to the whirring when the central heating pump went but when I go into the cupboard in the bathroom to check, its definately not the central heating pump making the noise. I have also tried changing the setting on the central heating pump when i put the hot water on, but it doesnt seem to make any difference. the central heating engineers think its the same type of whirring as water being forced through pipes, (hence they recommend power flush / new boiler) but I just find it strange it only happens with heating and hot water on, its fine when heating is just on??
It actually sounds as though something in the system somewhere is working harder when both are on (and struggling to do so).

I also phoned up another (3rd) central heating engineer and quoted the boiler make/model and he mentioned something about it having twin pumps (or valves? sorry cant remember which) in the boiler and that you cant get hold of replacement parts anymore (not sure if this is true or he was just trying to flog me a new boiler?) I guess it would make sense if there are two diff pumps (or valves etc) in the boiler and the one for the hot water was knackered, as this would explain why only noisy when hot water on. The few times I have tried it with hot water on and no heating its been noisy too, but not as noisy as when heating on also.

The noise seems to be worse when its cold - when hot water comes on in the morning, though as this is very early and i'm ususally asleep maybe I just notice it more as it wakes me up.

Thanks

AlanE · Posted: Mon May 05, 2008 5:51 pm Post subject:

eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Its an open vented system (not sealed),

Just unscrewed the bottom panel of the boiler, and on the reverse seems to be details / installation instructions - and model number. its a Myson Orion 50B.

AlanE · Posted: Mon May 05, 2008 7:49 pm Post subject:

Since I carry spare pumps as van stock I would be inclined to fit a standard pump and see the effect also partial blockage in cold feed could mean insufficient water so it might be noisy.

However this blockage would not require a powerflush to cure.

eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Thanks Alan

Just so I understand (and know what to pass on to the central heating engineer) could any standard pump be fitted? (presuming we are talking about the pump in the actual boiler itself rather than central heating pump?)

Also, is there any way of checking if the cold water feed is partially blocked? (and where would it be blocked, are we talking to the boiler itself of to the hot water cylinder?)

Also how much (approx) would you expect to be charged for the standard pump to be supplied and fitted?

AlanE · Posted: Tue May 06, 2008 8:27 am Post subject:

Not aware, off the top of head, that any Myson Orion had an internal pump. If it had why have you also got an external one??

eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Just to confuse things a little more (or maybe clear things up), I replaced the room thermostat as it was macking a ticking noise, which I understand happens sometimes when they wear out as the copper strip inside vibrates. Anway, replaced it with an electronic thermostat, but the programmer didnt seem to like it (the programmer is a honeywell, but the thermostat was a sunvic and kept blowing the fuse on the programmer downstairs. After more reading, it appears the two arent compatible, but it did actually throw up another issue. Because its been so hot the last few days, the heating hasnt been switched on (well hasnt got cold enough as it has been on constant, but the thermostat on the wall was set to 20 degrees. However there is also a thermostat on the hot water cylinder, and even if the hot water is turned to "off" on the programmer, the central heating pump keeps switching itself on (to warm up the hot water?) It goes off straight away when you turn the thermostat down on the hot water cylinder, and comes back on when you turn it up. This is with both hot water and heating turned off on programmer downstairs. Come to think of it, this has been happening for a while as the cupboard where the hot water tank is was always boiling hot, its just I never noticed that the central heating pump was on when it shouldnt have been as the heating has been on most of the time over the last few months.

Not sure if this explains why it so noisy when the hot water and heating are on at the same time, but it appears that the programmer is faulty??
Can you think of anything else that this could be before I buy a replacement programmer (and also replacement room thermostat).

also worth mentioning, that when the hot water is turned to "off" on the programmer downstairs, and the central heating pump is on, the boiler isnt fired up (ie heating anything up) all the time, but it is fired up all the time when the hot water is turned "on" on the programmer downstairs.

Also, are only the same manufacturers products compatible with each other? I intend to replace the programmer with the same make/model, but just wondered if this is the case or not.

Many thanks

AlanE · Posted: Sun May 11, 2008 5:00 pm Post subject:

Hope this doesn't make reply 'messy' but this way I can group answer with question without copying and quoting bite all the way through.

Just to confuse things a little more (or maybe clear things up), I replaced the room thermostat as it was macking a ticking noise, which I understand happens sometimes when they wear out as the copper strip inside vibrates.
Personally never heard of it, and what copper strip?
Anway, replaced it with an electronic thermostat, but the programmer didnt seem to like it (the programmer is a honeywell, but the thermostat was a sunvic and kept blowing the fuse on the programmer downstairs.
Only reason for this is incorrect wiring
After more reading, it appears the two arent compatible,
Who said and in what way?
but it did actually throw up another issue. Because its been so hot the last few days, the heating hasnt been switched on (well hasnt got cold enough as it has been on constant, but the thermostat on the wall was set to 20 degrees. However there is also a thermostat on the hot water cylinder, and even if the hot water is turned to "off" on the programmer, the central heating pump keeps switching itself on (to warm up the hot water?) It goes off straight away when you turn the thermostat down on the hot water cylinder, and comes back on when you turn it up. This is with both hot water and heating turned off on programmer downstairs. Come to think of it, this has been happening for a while as the cupboard where the hot water tank is was always boiling hot, its just I never noticed that the central heating pump was on when it shouldnt have been as the heating has been on most of the time over the last few months.

Not sure if this explains why it so noisy when the hot water and heating are on at the same time, but it appears that the programmer is faulty??See no reasoning in this diagnosis!
Can you think of anything else that this could be before I buy a replacement programmer (and also replacement room thermostat).

also worth mentioning, that when the hot water is turned to "off" on the programmer downstairs, and the central heating pump is on, the boiler isnt fired up (ie heating anything up) all the time, but it is fired up all the time when the hot water is turned "on" on the programmer downstairs.

Also, are only the same manufacturers products compatible with each other? I intend to replace the programmer with the same make/model, but just wondered if this is the case or not. No noway often find mix & match

AlanE · Posted: Sun May 11, 2008 5:13 pm Post subject:

Right firstly the motorised valve you have is not a standard 3 port valve. The Sunvic SDM1901 ref is the number for the actuator so first question is have you changed either the valve or activator, or both combined? This is because normal valves are srping return whereas the one you have is known as a MOMO which means whilst power is applied to a spring loaded valve to hold it in certain positions yours is opened under motor power and closed by motor power. Wiring is different.

Can you let us know model of programmer and replacement thermostat purchased (model of old stat might help)

Your boiler is a basic one and the pump is wired in parallel with boiler so pump should only run when power is supplied to boiler. That effectivly means that ALL the time a demand for heat exists boiler and pump are powered - boiler might switch on and off depending on BOILER thermostat setting and tempreature of water in it - but it has power at its in terminals.

By saying you have a Honeywell programmer I presume boiler DOES NOT have an internal timer.

Let me have above details and I'll try to sort wiring diagram for your system as it would seem yours may not be connected properly.

eholden · Joined: 31 Jan 2007 Posts: 8 Location: Bolton

Alan

Firstly - here are replies to your original comments in red...

Personally never heard of it, and what copper strip?
When you open up old thermostat there is a copper disk that raises up or down dependant on the temp you select (ie how much you turn the dial). Apparently when they get worn out they can get loose and make a ticking sound (it does it when it seems to be either warming up or cooling down as it makes the ticking noise just before the boiler fires up and turns the central heating on. This is what the central heating engineer told me when he came to look at the boiler.
Only reason for this is incorrect wiring
Yes, probably.. the honeywell one was wired differently to how the sunvic one should have been wired. We wired it up as per the instructions on the sunvic one, but this blew the fuse. We then tried about 10 other combinations, some blew the fuse straight away, some only blew the fuse when the water came on as well as the heating. There were 3 wires (so total of 27 poss comibinations) and we didnt have our multi meter at the time so couldnt really tell what was coming from which wire so after hours of messing about put old one back on.
Who said and in what way?
After reading instructions, it said it was only compatiable with other sunvic products. I didnt think this was the case as thought you could mix and match but didnt seem to like it.
See no reasoning in this diagnosis!
Clutching at straws may be my reasoning, it's driving me mad and no-one seems to be able to understand what it wrong with it:cry:

In answer to your other questions, I think we changed both combined. It was the complete unit with 3 ports coming out of the side. If you can tell me how to attach a picture I will send it to you (or email it, whatever is easier). The old one was a spring return as you could manually change from heating to hot water, but this one is definately motorised as you say. we changed it as a process of elimination as it wasnt working correctly, so may have either made things worse or at best just confused the matter, but maybe the system wasnt completely wired up correctly in the first place.

Boiler doesnt have an internal timer, the current model of programmer is an ST699B. The (old) thermostat is a honeywell T6360B. I took the new sunvic one back to B&Q today as I didnt think it was compatible, but open to suggestions for a replacement one.
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AlanE · Posted: Sun May 11, 2008 7:37 pm Post subject: