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Bosch greenstar 30 CDi - no central heating or hot water!

I had a brand new boiler installed by a recommended supplier in September 2008. It failed to heat the hot water . After some time and aggravation we were advised a new pump was required. This was fitted in November. By December it was not working again and we were getting no hot water from the boiler and by January 5th the central heating system was not working either. The lights are on, on the control panel.

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It sounds like the system was not cleaned properly when the new boiler was fitted. all new boilers need to have the pipework flushed to remove any debris scale sludge and flux from the system. this is now usually done by a power flush which is basically a big pump mounted on a big bucket and it washes the dirt out of the pipework and collects in the bucket. if this is not done the dirt will block up the small passages in the heat exchanger. i suggest the system is cleaned flush and the heat exchanger changed to help protect the boiler a filter should be fitted (for example a magna clean) if the company who installed the boiler is corgi registered then they are liable for the damages. call corgi for advice.

Posted on Mar 26, 2009


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Posted on Jan 02, 2017


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What is the best boiler for heating and hot water in Europe for a flat?

I would suggest the Wilford boiler is a great option. In particular, the Zhangjiagang Wilford Boiler as it is a combination boiler meaning it is small, can easily be stored in a cupboard and is economical to run. Get in touch with them to see if it is ideal for you.This brand of pressure hot water boiler is the best choice of transforming of the heating boiler of coal-fired. The horizontal structure of the boiler can absorb the heat with high efficiency ,heat transfer fully, the efficiency of heat transfer can reach 98%, and with good quality of steam, not pollution, no noise ,is the real green and environmental protection product. you can go its website for more
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May 08, 2017 | Miscellaneous


Boiler Replacement -When to do it

Your boiler is on the blink. Now you have some big decisions to make. Do I get another opinion? How much will it cost to replace the boiler as opposed to fixing it? How much energy will be saved? Home heating with a hot water heating system is a very good way to heat. However, when the boiler does not work or leaks there are many things to think about. The troubleshooting ideas in this article will work for both steam and hot water boilers.


If there is no water running out of the boiler and it is just a control issue it may be best to get another opinion. If there is water running then there is a stop leak liquid that can be placed into the boiler as a temporary fix. It should be viewed as temporary and not a permanent fix. Either a section of the boiler will have to be replaced or the boiler may need to be completely replaced.

If the boiler is fairly new and the warranty will pay for some of the cost then replacing a section may be the way to go. Bear in mind though, that the warranty rarely covers the labor cost. Labor will need to be paid by the homeowner. If the boiler is more than 20 years old then it is a no-brainer, replace it, the increased efficiency combined with the age of the existing boiler make it a simple decision. Oil boilers especially are very much on a down hill slope by 20 years, gas boilers are often in better shape even though the efficiency is way down from what today's are. So bottom line, replace if older than 20 years. For boilers in the 10-15 year range it is often a very difficult call. Work with your heating service expert to figure the best option and I would definitely get a second or even a third opinion.

The next cause of trouble could be a failure of the controls on the boiler. Once again I would go with the 20 year rule. Unless the control that failed is relatively inexpensive I would replace the boiler. Often I have seen that when one control fails other controls are soon to follow and the beast becomes a money pit. This is especially true of oil burners. Many new boilers now come with a five year full replacement warranty that even cover labor. Once again the really hard questions come for those boilers in that five to fifteen year old age bracket. The questions get even harder when you are without heat, it is freezing outside and you do not have the time to get other opinions. At this point you have very limited options. Do make sure that you get a cost for the repair before you give the permission to fix the boiler. Electrical controls are not returnable once they have been installed. So once installed you bought them.

Questions about boiler failure and replacement are many. This should give a brief overview of the options that are available for the homeowner. There are many variables and often no answer is the completely right one. Many things depend on the situation of the homeowner, the age of the boiler, the cost of the repair, and the efficiency of the existing boiler as opposed to the efficiency of a new boiler. Many times that all adds up to a judgment call between the homeowner and the heating company.

on Dec 06, 2009 | Heating & Cooling

1 Answer

Worcester 350 combi boiler on but water cold and radiators cold. Have put pressure up but made no difference. What's wrong with it?

If the inline pump is not working no hot water will flow into your radiators. The pump pushes the water in the lines to create a water flow. Increasing the pressure will not help in this case. I recommend you put the pressure back down as it usually is preset when the boiler is installed. My pump is about three feet back of the boiler on the intake line. If you don't know what you are doing I recommend getting a repair man as you could create more problems by over heating the boiler its self and blowing the electrical parts up.

Feb 06, 2015 | Water Water Heaters

1 Answer

Honeywell technical support

This boiler, from memory, has an electric diverter valve.
If the system has dirty (sludge/scale laden) water then the diverter valve may not return under spring pressure, and therefore not divert all of the hot boiler water to the hot water heat exchanger, leaving some going to the rads.
If I am right then the rads will not get fully hot.
If the valve has failed completely, or electrically, then the rads will get fully hot and there will be no hot water output (hot water will be cold).

Aug 19, 2014 | Heating & Cooling

1 Answer

Hi, I need your help please. I have steibel eltron gas boiler. Heating radiators and hot water. The water is leaking from the bottom of my boiler. It is orange / brown water. It stops dripping when the...

Either a seal or casting itself is cracked and leaking. Going to have to replace. Or they do make powder that will seal the leak. Most plumbing or HVAC suppliers do carry this. I have had to use it a few times and has never let me down.

Mar 27, 2010 | Heating & Cooling

1 Answer

Radiator heats up when running a shower.

Your boiler is overdue for a service.

Combi boilers are unlike regular boilers in that they have quite a few moving parts, it's vital that these are serviced annually if you want the boiler to remain reliable and to avoid expensive failures.

In your case, the diverter valve has most likely failed. Normally, when the heating is on this senses when there's a demand for hot water and temporarily diverts the primary hot water circuit to feed the domestic hot water heat exchanger. When the demand for hot water ceases the primary hot water circuit is diverted back to the central heating heat exchanger. The valve has a number of moving parts including a rubber diaphragm which can wear out and split and moving shafts which can seize.

When the valve fails it can leak and also can divert hot water to the central heating heat exchanger when hot water is used. The reason that only the highest radiators in the system are affected is probably because the failed valve does not necessarily cause the central heating pump to activate and circulate the hot water throughout the system (it does on some boilers though). If hot water is introduced into a cold heating system it will rise via convection to the highest points in the system like an old fashioned gravity circulation system which was unpumped.

Call a heating engineer out as soon as possible; I'm not going to advise how to do the repair yourself as gas appliances MUST be serviced by qualified persons only for reasons of safety. If you're lucky then the valve simply needs cleaning up and a few new diaphragms plus other minor seals and rings. If it's gone too far then the valve and possibly the manifold it's attached to will need to be replaced.

In the UK the part alone typically costs between £100 to £200 depending on whether it's just the valve or the manifold as well. The diaphragm kit typically costs up to around £15 and is routinely fitted when the boiler is annually serviced, and a new valve will already have new diaphragms fitted. For a routine service expect to pay for up to two hours labour (many can be done in one hour), but if the valve/manifold have failed it will be longer as one failure often causes other parts to need further inspection/repair.

I hope that I've helped you today, if so please return the favour by rating my answer.

Jul 10, 2009 | Whirlpool Aquatic Millennium VII -...

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No central heating back boiler

back boiler run from a gas fire? check the instructions to operate the gas heat to the back boiler not just the fire
I presume that this a fully pumped system - air lock doubtful There maybe on/off valves on the pipes to and from the back boiler [situate close to cylinder] make sure they are on - anticlockwise turn
or there could be a blockage in the outlet from header tank usually in the loft. or If there is no water in it maybe the mains cold feed it is off.
Note if no water in it DO NOT USE the back boiler

May 03, 2009 | Bosch & Power Vent Water Heater

1 Answer

Open vent central heating

yes it is possible toupgrade the system to a sealed one using a system boiler as you mentioned. the thing to bear in mind is to upgrade the radiator valves to pressure rated ones 10bar.
The probable cause of the over heating is down to the system being sludged up/cold feed blocked, or possible pump circulating problem?
I would recommend the installation of a magna clean filter to help keep the new boiler clear from system debris.I would definately power flush the system, if the system is a twin two port valve system then a automatic bypass should be fitted, all of this done by a corgi registered gas engineer



Dec 18, 2008 | Protech Systems FasNSeal FSWMKE4 4" Vent...

1 Answer

Installing a Mixer Shower from a Combi Boiler.

hi there, your boiler will perfectly match the mira excel ( a great choice i might add) a 24cdi will give about 9.8 litres a minute flow rate hot water.
The mira excel is suitable for any plumbing set up and there installation instruction are very well laid out & their helpline is fantastic.
The hot water will fluctuate accordingly to the time of year as the cold water temp coming into the property will vary. but the boiler will modulate to compensate.So in brief in the summer you will notice it hotter than you would in the winter, this has nothing to do with the boiler just the incoming temp of the cold water.



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